Preheat the oven to 350°F (175°C). Grease and line a baking pan with parchment paper.

In a mixing bowl, whisk together the melted butter and sugar until smooth.

Add the eggs one at a time, mixing well after each addition. Stir in the vanilla extract.

Sift in the flour, cocoa powder, and salt. Mix until just combined.

Pour half of the brownie batter into the prepared baking pan and spread evenly.

Place the halved Cadbury Eggs on top of the batter, cut side up.

Pour the remaining brownie batter over the Cadbury Eggs, spreading it to cover them completely.

Bake in the preheated oven for 25-30 minutes or until a toothpick inserted into the center comes out with a few moist crumbs.

Allow to cool in the pan before cutting into squares.