Brownie Batter

1. Preheat the oven to 350F and coat the inside of an 8×8 pan with nonstick spray. Press in a sheet of parchment paper to cover the bottom and two sides, allowing the paper to hang over the sides for easy removal.
2. In a medium saucepan over medium heat, melt down the butter and coconut oil. Once melted, whisk in the cocoa powder and bubble for 30 seconds. Remove from heat and stir in the chocolate chips to melt.
3. In a large mixing bowl, vigorously whisk together the sugars and eggs until the mixture becomes pale yellow and slightly thickened, about 1 minute. 
4. Whisk in the salt and vanilla, followed by the chocolate mixture.
5. Last, whisk in the flour just until combined.
6. Pour the batter into the pan and spread evenly. Lay the Oreo cookies on top in 4 rows of 4, staggering the rows as much as possible and cutting some cookies to fully fit the pan. Just slightly press them into the batter. Place the pan in the refrigerator while we make the monster dough. 

Monster Cookie Dough

1. In a large bowl, whisk together the peanut butter, coconut oil, and brown sugar until smooth and combined.
2. Then whisk in the egg and vanilla, followed by the baking powder and salt.
3. Now switch to a rubber spatula and stir in the oats and flour just until combined. It will make a very shiny and smooth dough.
4. Last, fold in the chocolate chips and Reese’s Pieces. 
5. Scoop the dough on top of the Oreo layer, scattering it around the surface. Very carefully spread it out as we do not want to disrupt the layers underneath. 
6. Once level, top with a handful more of chocolate chips and Reese’s Pieces. Gently press into the surface and bake for 25 to 30 minutes. They’re done when the edges are golden and the surface is no longer glossy.
7. Top with flaky sea salt and allow to cool at room temperature for about 20 minutes, then transfer to the refrigerator to cool completely for about an hour or until the pan is no longer warm.
8. To release, run a knife along the edges and lift the bars out of the pan. Slice into 16 squares and enjoy!