Combine your flour, sugar, cocoa and salt.
Add your eggs, oil and vanilla. Be sure not to over mix.
Add your Cadbury eggs. Hold a few whole eggs back to top the brownie batter with so you can see them after baking.
Pour into a greased or parchment papered pan. The pan size will determine the baking time. I'd recommend an 8x8 or a 9x13.
Bake at 350 degrees. If using a 9x13 pan bake for 25-30 minutes. If using an 8x8 pan bake for 55-60 minutes. Check periodically with a toothpick to see if baking is complete.
Allow to cool fully, then transfer to a cooling rack.
If cutting out shapes, use a cookie cutter to cut out your brownies.