1. Preheat the oven to 350°F and line a 9×9-inch baking pan with parchment paper.

2. In a large bowl, stir the melted butter, brown sugar, and granulated sugar until smooth and glossy.

3. Add the eggs and vanilla extract, then mix until fully combined.

4. In a separate bowl, whisk together the flour, cornstarch, baking powder, and salt.

5. Fold the dry ingredients into the wet mixture just until a soft dough forms.

6. Stir in the white chocolate chips, semi-sweet chocolate chips, and most of the candy-coated Easter eggs.

7. Press the dough evenly into the prepared pan and scatter the remaining Easter eggs over the top.

8. Bake for 25 to 30 minutes, or until the edges are lightly golden and the center looks set.

9. Cool completely in the pan before lifting out and slicing into bars.