Brownies:

Preheat oven to 350° F / 175° C. Line an 8×8-inch square baking tin with parchment, allowing a 1-inch overhang on all sides.

Melt butter in a saucepan over medium heat.

Add granulated sugar, cocoa powder, and fine sea salt and stir until a thick, grainy paste forms.

Scoop into a large mixing bowl and allow mixture to cool slightly, about 5 minutes.

Stir in eggs and vanilla bean paste.

With a rubber spatula, fold in all purpose flour, baking powder, espresso powder, and canola oil, stirring until just barely combined. Do not overmix. (Batter will be thick).

Fold in milk chocolate chips and miniature Cadbury eggs.

Pour into prepared tin.

With a rubber spatula, spread batter evenly across entire surface.

Bake in preheated oven for 35-40 minutes, or until a cake tester or toothpick comes out mostly clean. Sit tin on a wire rack and allow to cool completely, at least 2 hours.

Chocolate Frosting:

In a large mixing bowl or the bowl of a stand mixer, whip butter on high speed until light and fluffy.

Add cocoa powder, vanilla extract, and confectioner’s sugar, and mix until well-combined.

Gradually add the whipping cream, a small amount at a time, until smooth and creamy. If necessary, add a bit more cream or confectioner’s sugar to adjust consistency. Frosting should be spreadable, but not runny.

Lifting by the parchment overhang, remove cooled brownie slab from tin.

With a small stepped palette knife or rubber spatula, spread chocolate frosting over cooled brownies.

With a sharp chef’s knife, slice into squares and serve.

Store Cadbury egg brownies in an airtight container in the refrigerator for up to 5 days.