01 - Preheat oven to 350°F. Line an 8x8-inch baking pan with parchment paper, allowing an overhang for easy removal later.
02 - Whisk together flour, baking powder, and salt in a bowl. Set aside for later use.
03 - Combine melted butter and brown sugar in a large mixing bowl. Stir until smooth and fully incorporated.
04 - Beat in the egg and vanilla extract until the mixture is uniform and well-blended.
05 - Gently fold the dry ingredients into the wet mixture using a spatula. Mix just until combined—avoid overmixing to prevent dense blondies.
06 - Fold in white chocolate chips, milk chocolate chips, and chopped Cadbury Mini Eggs until evenly distributed.
07 - Spread batter evenly into the prepared pan. Press reserved whole Mini Eggs lightly into the surface for decoration.
08 - Bake for 22 to 25 minutes until golden on top. A toothpick inserted in the center should emerge with a few moist crumbs.
09 - Cool completely in the pan. Lift out using parchment paper overhang and slice into 12 squares.