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Tuesday made better with Monster Oatmeal Chocolate Chip Cookie Bars for snacking. These one bowl homemade oatmeal cookie bars with chocolate chips and Reese’s Pieces are the perfect way to use up any leftover Halloween candy. They’re super easy, festive for both Halloween and Thanksgiving, and most importantly, everyone LOVES them!
It’s been so long since I shared a simple cookie bar. But with Halloween right around the corner, I figured now was the perfect time.
We don’t get trick-or-treaters up here where we are, it’s a little too rural. Asher goes into Frisco where she goes to school and where the businesses on Main Street hand out candy. But she never brings much, if any, home. In general, we really don’t eat candy, and I don’t usually love using candy in my baking recipes. But sometimes, mostly for fun holidays like Halloween and Christmas, I cave in and throw some candy into recipes.
The Halloween candies that we always have a lot of around here…M&M’s and Reese’s Pieces. I tend to buy way more than we’ll actually ever eat. I get so excited when they come out with the fall colors…followed by the holiday colors (I’m such a sucker for any kind of holiday packaging), that I buy one too many bags and never know what to do with them all.
Enter these cookies bars. I mean, it’s Halloween, so I figure, if there’s ever a time to have fun with a candy filled recipe, it’s now. You know?
A simple oatmeal cookie base studded with chocolate chips and your favorite leftover Halloween candy. I used Reese’s Pieces, but M&M’s or your favorite chopped up candy bar would be great too. Use what you, your family, and friends love most.
As you can guess, these are pretty easy to make.
I used my mom’s oatmeal chocolate chip cookie recipe as a base (which is from the HBH cookbook). Then I stirred in some candy pieces (again, use your favorite, chopped Reese’s would be so good too). I also decided to bake the cookies into bars, instead of round cookies. Mom’s recipe is honestly the BEST. Nothing beats it, and the fact that it’s a one bowl and done kind of recipe makes them that much better.
Bonus? I pretty much always have the ingredients on hand. So it’s the perfect recipe to bake up whenever a craving for oatmeal cookies hits. And yes, along with this bar being easy to make, they’re also so delicious. Best oatmeal cookies. Ever.
And I really mean it.
I baked these up with my little sister, Asher in mind. She’s been begging me to make cookies. She has a class Halloween party coming up that I promised to bake something for, so we tested these cookie bars out over the weekend. These are full on Asher approved. The thing with kids? They tend to be picky, so I knew I could be getting into trouble with the oatmeal cookie. But I really wanted to bake up something other than just another chocolate chip cookie. Been there done that. I was worried, but when she came down to the studio on Saturday, she ended up loving every bite. She could not get enough.
Granted, she loved the “Halloween” colored candies. But she also said the cookies were delicious. She’s so excited to make them again for her Halloween party.
Side Note: Asher is now ten. When I asked her what she was going to be this year, she said, “you’ll have to wait until Halloween to find out”. And with sass. Ugh. I wish she’d just stop growing up already!
Whenever I make the recipes I grew up baking with my mom, those more classic recipes, I always ask myself, why don’t I bake these more. Obviously it’s because I am constantly testing out new recipes. But it’s a bummer that it’s hard to find time to bake anything that’s “old” and from the archives. I’m glad I decided to dust this recipe off and share it with you guys.
Sometimes I forget that it’s the classic recipes that are really the greatest. Hands down a favorite recipe of the month. And I love that these are fun for both Halloween and Thanksgiving.
If you make these cookie bars please be sure to leave a comment and/or give this recipe a rating! Above all, I love to hear from you guys and always do my best to respond to each and every comment. And of course, if you do make this recipe, don’t forget to also tag me on Instagram! Looking through the photos of recipes you all have made is my favorite!
Monster Oatmeal Chocolate Chip Cookie Bars
Servings: 18 cookie bars
Calories Per Serving: 1732 kcal
Nutritional information is only an estimate. The accuracy of the nutritional information for any recipe on this site is not guaranteed.
Ingredients
- 2 1/2 cups old fashioned oats
- 2 cups all-purpose flour
- 1 cup brown sugar packed
- 1/2 cup granulated sugar
- 1 teaspoon baking soda
- 1 teaspoon salt
- 1 cup canola oil
- 2 large eggs
- 1 tablespoon vanilla extract
- 1 1/2 cups semi-sweet chocolate chips
- 1/2 cup Reese's pieces or M&M's
Instructions
- 1. Preheat the oven to 350 degrees F. Grease a 9x13 inch baking dish with butter or line with parchment paper. 2. In a large mixing bowl or the bowl of a stand mixer, mix the oatmeal, flour, brown sugar, granulated sugar, baking soda, salt, canola oil, eggs and vanilla. Beat until the dough is moist and all the ingredients are combined. The dough will be crumbly. Mix in the chocolate chips and 1/4 cup candy pieces.3. Press the dough into the prepared baking dish and scatter the remaining 1/4 cup candy over top. Transfer to the oven and bake 18-20 minutes or until the edges are set and the bars are golden. Let cool and then cut into bars.
Made these this week and they’re AWESOME! Simple yet decadent and yummy. I ended up needing to cook mine for several more minutes than you suggested to get them cooked through but maybe my oven is weird. Either way, another WIN from Half Baked Harvest đŸ™‚
I am so glad you loved these bars, Kate! Thank you!!
These cookies were a hit. They couldn’t have come together easier (I think from the time i started baking, it took ten minutes to get them into the oven) and everyone who tried them loved them. I used quick oats instead of traditional oats because that’s what I had, and they turned out just fine– probably less chewy, but the cookie texture was perfect and they held up fine. I can see myself using this recipe time after time and using seasonal M&Ms for various holidays. Thank you for the great recipe!
Thank you so much Caitlin! I am so glad you loved this recipe and hope you love others on my blog as well!
Loved these! They were super simple and perfect to bake up on Halloween and share with friends! I am excited to do the same around Christmastime with seasonal M&Ms đŸ˜€ This is a great option when you want a great homemade treat, but don’t have a lot of time. Thanks!
Thank you so much Lisa! I am glad these turned out amazing for you!
I made these the other day and they were fantastic! So easy and so delicious. I really like the texture of the oatmeal giving it a nice chew and the bar was not dry. Thanks for creating and sharing so many awesome recipes!
This is so sweet! I am so glad you loved these bars, Melissa! Thank you!
made this yesterday… and it taste greatttttt… Marvelous.. my new fav oatmeal dessert/snack … not good looking as yours but tasty đŸ™‚ you got a new fan
I am so happy to hear that! Thank you Micheal!
These were a hit at my work’s Halloween potluck lunch! Definitely recommend.
YES! So happy to hear that Jenna! Thank you!
I made this and love it! So perfect for a fall potluck. The Reese’s are great fall colors. I baked this at about 5200 feet and probably should have cut down my baking soda slightly and upped the temp to bake, but they still came out wonderfully!
Thank you!
I am so happy to hear that! Thank you so much Nicole!
Could you freeze these? Would you bake then freeze or freeze raw and bake?
HI! I have never frozen cookie bars, so I am not sure for sure. I would freeze after baking and then thaw on the counter. Please let me know if you have any other questions. I hope you love this recipe. Thanks so much! xTieghan
can I substitute the oil
for the coconut one?
HI! Yes, you can use coconut oil, but I do prefer canola oil. Please let me know if you have any other questions. I hope you love this recipe. Thanks so much! xTieghan
could a different oil be used instead of canola? Coconut maybe?
HI! Yes, you can use melted coconut oil, though I prefer canola oil. Please let me know if you have any other questions. I hope you love this recipe. Thanks so much! xTieghan
can you make these with butter, or a combo of butter and oil?
HI! You can use melted butter, but I do like oil best. Please let me know if you have any other questions. I hope you love this recipe. Thanks so much! xTieghan
these look delicious – i love monster cookies and anything reese’s so i’ll definitely be making them soon! i hate to be “that person”, especially because this is a dessert so you *shouldn’t* be eating a ton of it, but 1 cup of oil seems like a lot. any suggestions for another liquid? maybe a half oil, half applesauce kind of thing?
Hi! You can use 1/2 oil and 1/2 applesauce. While it is not quite the same, it’s still pretty good. Please let me know if you have any other questions. I hope you love this recipe. Thanks so much! xTieghan
I love these bars, what a perfect Halloween treat!
Thank you so much!
Hi I made ur lovely recipe but I used raisins instead of chocolate. (What I had in the house) I also subbed 1/2 cup raw stevia for the 1/2 cup white sugar, so I’m sorry to ask. Substitutions do not guarantee a perfect recipe, I know. They taste great but won’t hold together well to cut bars. What should I do differently next time? Another egg? Thank u!
Hi! So my guess is they are not holding together because of the stevia. I don’t love baking with stevia and have had issues with it in the past, so that’s just my guess! Not sure how to correct the problem as I have not tested the recipe that way you have made it. Sorry I could not help more, but glad you are enjoying the bars. Thanks so much! xTieghan
I live in an apartment on my university campus, so I am certain we won’t be seeing any trick-or-treaters anytime soon. In my opinion, that’s a GOOD thing because I don’t have to share ANY CANDY. HAHAHAHA. But in all seriousness, this recipe is divine! I’d prefer this over candy any day given that I like my desserts comforting and hearty. It’s so easy to down so many peanut butter cups and chocolate in a sitting. NOT EVEN FUNNY.
Thank you so much Cassie! I am so glad you like this recipe and I hope you have an amazing Halloween!