Preheat the oven to 350°F. Line an 8 by 8-inch baking pan with parchment paper.
In a bowl, add pancake mix, cocoa powder, sugar, and baking powder. Whisk together until well combined.
In a large bowl, add melted butter, eggs, milk. Whisk until evenly combined and no egg streaks remain.
Add in dry ingredients. Mix until evenly blended.
Pour batter into the prepared baking pan, decorate with chocolate.
Bake for 60-70 min or until mochi is set. A toothpick inserted should come out mostly clean. Let mochi brownies cool completely before slicing and serving.