Preheat your oven to 350°F (175°C) and line two cupcake pans with liners.

In a large mixing bowl, whisk together the all-purpose flour, granulated sugar, unsweetened cocoa powder, baking powder, and salt.

In another bowl, whisk together eggs, milk, and vegetable oil until well mixed.

Gradually mix the wet ingredients into the dry ingredients until just combined.

Fill each cupcake liner halfway with batter and press a Mini Cadbury Creme Egg into the center.

Bake for 18-20 minutes. Check for doneness with a toothpick; it should come out clean.

Let the cupcakes cool in the pans for 5 minutes, then transfer to a wire rack to cool completely.

Beat butter until fluffy, then gradually mix in powdered sugar and vanilla until smooth. Add food coloring if desired.

Frost each cupcake once cooled, using a piping bag to create decorative swirls.