Melt butter in microwave safe bowl; in another bowl, add the granulated and brown sugars. Pour the melted butter over the sugars and let sit for several minutes.
While butter mixture cools slightly, measure out flour, baking soda, and salt, and whisk together in a bowl.
Into the butter and sugar, add egg and vanilla, and then gradually stir in the dry ingredients. Mix in your chocolate chips.
Scoop tablespoonfuls of dough onto a lined baking sheet, spaced about 2 inches apart. Press 2-3 Cadbury eggs into the top of each spoonful of dough.
Bake for 8-10 minutes. After removing from the oven, let the cookies stay on the pan for about 10 minutes before transferring to a cooling rack.
Notes
Store in an airtight container or gallon size plastic bag.