Preheat the oven to 350 degrees. Grease a 9x13 inch baking dish or line with foil or parchment paper.
To make the brownie batter - Add the butter and 2 ounces milk chocolate to a medium size mixing bowl that is microwave safe. Microwave the butter and chocolate on 30 second intervals, stirring after each interval until melted and smooth. This takes me about 1 minute and 30 seconds.
To the melted chocolate mixture add the sugar and instant coffee, whisking until completely combined. Add the vanilla and egg and whisk until smooth. Stir in the cocoa powder, flour and salt until smooth and just combined, try not to over mix the batter. It will be thick. Add 1/4 cup of the melted peanut butter (you will use the remaining 1/4 cup later) and gently stir, leaving a few streaks of peanut butter. Stir in the remaining chocolate chips or chunks.
To make the oatmeal cookies - In a large mixing bowl or bowl of a stand mixer, add the oatmeal, flour, brown sugar, baking soda, salt, melted coconut oil, egg, and vanilla and beat until combined and the dough holds together (the dough will seem oily, this is good, if not add a tablespoon more of oil). Mix in about 1/2 cup of the chocolate chunks.
To assemble drop dollops of about half the brownie batter into the prepared pan. Sprinkle the oatmeal cookie dough around and over the brownie batter. Dollop the remaining brownie batter over top the oatmeal cookie dough. If needed, re-warm the remaining 1/4 cup of peanut butter in the microwave and then drizzle it over the the pan. Use a sharp knife to swirl the peanut butter around the brownie batter (don't try to swirl the peanut butter around the oatmeal cookie dough). Now grab the remaining chocolate and scatter it over the pan.
Bake for about 25-35 minutes, just do not over bake. Underdone is always better in my opinion. Allow bars to cool in pan for at least 1 hour before slicing and serving.