01 - Preheat your oven to 350°F. Line an 8x8-inch baking pan with parchment paper, leaving an overhang for easy removal.
02 - In a bowl, whisk together the flour, baking powder, and salt. Set aside.
03 - In a large mixing bowl, combine the melted butter and brown sugar. Mix until smooth.
04 - Beat in the egg and vanilla extract until fully incorporated.
05 - Gently fold the dry ingredients into the wet ingredients with a spatula until just combined—do not overmix.
06 - Fold in the white chocolate chips, milk chocolate chips (if using), and chopped Cadbury Mini Eggs.
07 - Spread the batter evenly into the prepared pan. Sprinkle reserved whole Mini Eggs on top, pressing them lightly into the batter.
08 - Bake for 22–25 minutes until the top is golden and a toothpick inserted in the center comes out with a few moist crumbs.
09 - Let cool completely in the pan. Once cooled, lift out using the parchment paper and cut into 12 squares.