Preheat oven to 350°F (175°C) and line an 8x8 inch square baking pan with parchment paper.
In a large bowl, whisk the melted butter and granulated sugar until well combined.
Add the eggs and vanilla extract, whisking until the mixture is smooth and slightly glossy.
Sift in the cocoa powder, flour, and salt; fold gently with a spatula until just combined.
Fold in the semi-sweet chocolate chips.
Pour the batter into the prepared pan and spread evenly.
Bake for 20 to 25 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs.
Remove from oven and immediately press the chocolate mini eggs and pastel candies into the surface of the warm brownies.
Allow to cool completely in the pan on a wire rack before lifting out and slicing into 12 squares.