Preheat oven to 350°.
Melt butter in a small saucepan. Add chocolate and espresso to the melted butter and stir until melted and well mixed. Remove from heat and allow to cool a few minutes as you prepare your pan.
Spray a 9X13" baking pan with non-stick spray and line with parchment paper, allowing some to hang over the sides to act as handles for lifting the brownies out at the end.
Sift flour, cocoa powder, salt, and baking powder together in a bowl. Set aside. Now you have a saucepan with the chocolate mixture, and a bowl with a flour mixture. Got it? Good.
Whisk the sugars into the chocolate mixture until fully combined. Add in eggs and whisk well. Fold the flour mixture in by hand just until the last bits of flour have completely mixed in.
Spread into prepared pan (it's a thin layer) and bake in 350° oven for 15-20 minutes, turning the pan around half way through. Once the time's up, check it with a toothpick. Just poke it in to the center. If it comes out with just a bit of chocolate crumbs, you’re good. If it's got some extra gooey bits on it, give it a few more minutes and check again. Allow to cool on a wire rack while you prepare the top layer.
In a heat proof bowl set over a pot of simmering water, melt chocolate, peanut butter, and coconut oil, mixing until smooth. Fold in the cereal. Spread mixture in a smooth layer on top of brownies and sprinkle with the chopped peanut butter cups. Lightly press the larger pieces to adhere to the surface. Chill for at least 90 minutes in the refrigerator or overnight on the counter before cutting and serving.