Preheat oven to 180°C (350°F) and line a baking pan with parchment paper.
In a bowl, mix melted butter, granulated sugar, and brown sugar until smooth.
Add eggs one at a time, mixing well after each. Stir in vanilla extract.
Sift in flour, cocoa powder, salt, and baking powder. Mix gently until combined.
Fold in chocolate chips.
Pour batter into prepared pan and spread evenly.
Bake for 25–30 minutes until edges are set and center is slightly soft.
Remove from oven and immediately press mini chocolate eggs on top.
Add sprinkles and drizzle melted white chocolate if desired.
Let cool completely before cutting into squares.