Preheat the oven to 350 F degrees. Line a 8x8 inch baking pan with parchment paper, and spray with nonstick spray.
Add the melted butter to a large bowl, and add in the sugars and stir for 2 to 3 minutes until the butter starts to cool down, and thickens a bit. 1/2 cup melted butter, 3/4 cup granulated sugar, 1/4 cup brown sugar
Add the eggs and vanilla and mix until combined. 2 large eggs, 1 tsp vanilla extract
Add the dry ingredients into a medium bowl, and whisk them together. 1/2 cup all purpose flour, 1/3 cup unsweetened cocoa powder, 1/2 tsp salt
Slowly stir the dry ingredients into the wet ingredients and mix until just combined.
Add in 1 cup of the chopped Mini Eggs and fold it into the chocolate batter until evenly mixed. 1 1/2 cup Cadbury Mini Eggs
Scoop the mixture into the prepared pan and spread the batter evenly on the top.
Sprinkle about 1/4 cup of the remaining Mini Egg chocolate pieces on top of the brownies.
Bake for 22 to 30 minutes, or until a toothpick inserted in the middle has a few moist crumbs (but no wet batter).
While still warm, press additional Egg pieces on top of the brownies, for looks.
Let the brownies cool completely in the pan before slicing and enjoying.