Preheat the oven to 350 degrees, line a baking sheet w/ parchment paper, and unwrap the Cadbury Eggs. Set aside.
Unfold one sheet of puff pastry on a floured surface and roll out into a 10 inch square. Cut the sheet into 12 even squares.
Roll the mini Cadbury Eggs up into one piece of dough and shape into an egg shape, making sure to pinch closed any holes. Repeat until all of the Mini Cadbury Eggs have been used.
Brush the outside of the dough w/ the beaten egg, sprinkle w/ colored sugar, and bake for 12-15 minutes or until golden brown. Note: If using sprinkles other than colored sugar, add these on in the last few minutes or right at the end of baking, or they will melt in the oven.
Allow to cool on the baking sheet for 5-10 minutes before removing to a wire rack to cool completely.