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Spooky Black Widow Peanut Butter Bars. Doughy buttery, peanut butter cookie base, layered with creamy peanut butter, and the most delectable, roll your eyes back good, chocolate frosting that’s rich and fudgy. They’re sweet, salty, heavy on the peanut butter, extra chocolatey, and totally decked out for Halloween. The perfect spooky treat to enjoy all October long.

Black Widow Peanut Butter Bars | halfbakedharvest.com

It’s spooky season! I know it’s a little dorky, but I’m so excited for the Halloween season this year. I’m having so much fun creating Halloween themed desserts and drinks for the month.

I figured these would be the perfect spooky bars to kick off the month of all things spooky. Their so easy to make, delicious, and in my opinion, so cute too!

I love the little spider web and black spiders all around.

Black Widow Peanut Butter Bars | halfbakedharvest.com

The details

I tried to keep these as simple as possible, using my favorite peanut butter bars as a base and sweet chocolate icing.

Start with the peanut cookie base. These don’t even require a mixer, just mix with a spoon and bake. So simple. As soon as the peanut bars come out of the oven, dollop them with a hefty amount of creamy peanut butter. The key is to add the peanut butter while the bars are still warm. The heat from the bars allows the peanut butter to melt into one even layer and makes spreading the peanut butter out very simple.

Now let the bars chill completely.

Black Widow Peanut Butter Bars | halfbakedharvest.com

(spiders body with melted chocolate)

Black Widow Peanut Butter Bars | halfbakedharvest.com

(spiders after adding the eyes and legs)

Black Widow Peanut Butter Bars | halfbakedharvest.com

In the meantime, make the frosting.

The frosting needs to be thick and fudgy, but yet soft and almost runny. Think of a just set top that has glazed over and stiffened, but then underneath is fudgy, loose frosting.

The mix of ingredients is basic…butter, sugar, cocoa powder, vanilla, and milk.

Black Widow Peanut Butter Bars | halfbakedharvest.com

Now the decorating, start with the web

For the web, I used melted marshmallows and stretched the marshmallows over the set bars. It’s the easiest thing, and honestly, really fun. If you have kids, this is a fun task for them to do.

For the spiders, I used chocolate whoppers, a little melted chocolate, and some sprinkles. Now, here’s what I will say about the spiders, if you want to use small plastic spiders, go for it! Those will be really cute and people will easily be able to pick them off if they choose.

Black Widow Peanut Butter Bars | halfbakedharvest.com

If you want to make them homemade, that’s great too, it’s just going to take a little more time. I advise you to really use the photos for guidance, but I did my best to explain the process.

Two whopper balls for the spider’s back, melted chocolate for the legs, and then a couple of candy eyes.

Black Widow Peanut Butter Bars | halfbakedharvest.com

And that’s it! Aside from the spiders, really simple, and so fun to make! These bars are so great to enjoy all month long. Take them to your next Halloween party, and then of course…serve them up on Halloween night!

See you all tomorrow for our first Halloween cocktail of the season!

Black Widow Peanut Butter Bars | halfbakedharvest.com

Looking for other fall soup recipes? Here are a few ideas: 

Hocus Pocus Spellbook Brownies

Spooky Halloween Pretzels

BOO! Chocolate Peanut Butter Bars

Lastly, if you make these Black Widow Peanut Butter Bars 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 tag me on Instagram! Looking through the photos of recipes you all have made is my favorite!

Black Widow Peanut Butter Bars

Prep Time 50 minutes
Cook Time 20 minutes
Total Time 1 hour 10 minutes
Servings: 24 bars
Calories Per Serving: 252 kcal

Nutritional information is only an estimate. The accuracy of the nutritional information for any recipe on this site is not guaranteed.

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Ingredients

Peanut Butter Bars

Icing

For decorating

Instructions

  • 1. Preheat the oven to 350° F. Line a 9×13 inch baking dish with parchment paper.
    2. In a microwave safe bowl, melt together the butter and 1/2 cup peanut butter, stirring every 30 seconds until melted. Stir in the brown sugar, sugar, eggs, and vanilla. Add the flour, baking powder, and salt.
    3. Press/spread the dough out into the prepared dish. Transfer to the oven and bake for 18-22 minutes, until just set in the center. Remove from the oven and dollop tablespoon size spoonfuls of the peanut butter over the bars. Lightly spread the peanut butter in an even layer. Let cool completely.
    4. To make the frosting. Add the butter, 2 cups powdered sugar, cocoa powder, vanilla, and 1/4 cup warm milk to the bowl of a stand mixer. Beat until smooth, adding additional warm milk until the frosting becomes thicker but still drizzly. Taste, adding more sugar if needed. Spread the frosting over the bars. Let set for 1-ish hour.
    5. To make the web, melt the marshmallows in the microwave on 30 second intervals, stirring after each, until melted and smooth. Let cool 3-5 minutes and then use your hands to stretch/pull the melted marshmallow over the bars to create a spider web. Go in as many directions as possible. It will be messy, but fun!
    6. To make the spiders, line a baking sheet with parchment paper. Spoon the chocolate into a piping bag with a fine tip or ziplock bag with the corner snipped off. Pipe two small, 1/3 inch dots of chocolate onto the paper side by side. Place 1 whopper on each dot, then draw 2-3 legs on either side of the whoppers for the legs. Sprinkle the legs with sprinkles. Place two tiny dots on either side of 1 whopper for the eyes. Place the tray in the freezer for 15 minutes to harden, then gently peel away the spiders and place them on top of the bars. Slice and enjoy!
    7. Store the bars in a cool dry place, either in the fridge or at room temp.
Black Widow Peanut Butter Bars | halfbakedharvest.com

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Comments

  1. 5 stars
    OK made these a second time as a double batch. This time my butter was fully room temperature and there was definitely a change in consistency for the icing. My kids were distracting me and I ended up cooking the base a bit too long. Definitely better when it’s not so crisp. I didn’t measure my peanut butter but I used a whole costco size tub and I should have used more. I also used less powdered sugar (even though I tasted it and thought it was OK…) more is better.
    I attempted the webs one more time and it was still an awful mess. I shopped for more eyes at the grocery store and they were all sold out so with the silver sprinkles they looked more like tarantulas.
    So for next time:
    -Cool butter
    – More peanut butter
    -More powdered sugar
    – White chocolate web
    Thanks again! Like I said before everyone loved them so I had to double up this time. I’m sure I’lll have to make it again before the month is up.

  2. So excited to make these for a Halloween party! How far in advance could they be made and still look like I made them the same day? Trying to squeeze some baking in with a newborn!

  3. 5 stars
    Hi There! Are your recipes adjusted for lower altitude bakers or are all measurements/temps/times for higher altitude? I just moved back to CO and am trying to readjust my recipes 🙂

  4. 5 stars
    Made these for my neighbors who all have the same birthday and happen to LOVE peanut butter. They were a success and quickly devoured. Didn’t have good luck with the marshmallow spider web like you did but they didn’t care!

  5. This was an easy fun recipe to make. Everything turned out perfect…….except for the marshmallows. I just COULD NOT get the “webs” to stick to the top of the icing. They wanted to stick to everything else, but not the icing. Does anyone have any suggestions?? The spiders, however, came out so cute!!! Even the 8 and 11-year old helped make those, but those darn spiderwebs were awful. I like Andrea S idea of just piping on white chocolate next time. Thanks for this recipe and all your other recipes!!

    1. Hi Karen! I’m so sorry about those darn webs! They can be sticky and troublesome at times. Did you let the frosting set a little bit before trying to apply the webs? xTieghan

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