Buckeye brownies are known for their three layers of rich decadent goodness! A fudgy brownie base gets a sweet peanut butter layer then topped with chocolate ganache. It's a chocolate peanut butter lover's dream brownie!
Preheat the oven to 350 degrees Fahrenheit. Grease a 9x13 pan and line with parchment paper leaving a 1-inch overhang on both sides.
In a large bowl, melt the chocolate and butter together in 30-second intervals. Once fully melted, stir in the sugars and eggs.
In a medium bowl, sift together the salt, cornstarch, baking powder, cocoa powder, and flour. Add the dry ingredients to the wet and mix until combined.
Add the brownie batter to the prepared pan and smooth with a spatula. Bake for 40-45 minutes, until a toothpick comes out clean from the center.
Let the brownies cool completely before adding the other layers.
Peanut Butter Layer
Add the peanut butter and butter to a large bowl and beat with a hand mixer until smooth.
Add the vanilla, powdered sugar, and milk and mix until combined and creamy.
Scoop or spoon the peanut butter mixture on top of the cooled brownies and use an offset spatula or knife to spread it evenly over the top, making it as smooth as you can.
Ganache
Place the chocolate chips and oil in a bowl and heat in the microwave at 20-second intervals, stirring until melted and smooth. It should be about 40-60 seconds total.
Pour the ganache over the peanut butter topping and smooth. Place the pan in the fridge for at least 30 minutes to chill.
Once the ganache is set, remove it from the fridge and lift the brownies from the pan. Slice into pieces and serve.