Preheat oven to 350°F (180°C) and line 2 baking sheets with parchment paper.
In a large mixing bowl or stand mixer, beat butter and sugars until pale in color, light and fluffy.
Add egg and vanilla until just combined.
Gradually add flour, baking soda and salt until just combined. If needed, use your hands to press dough together.
Crush half of the Cadbury Mini Eggs and fold into the dough, reserving the remainder to press on top just before baking.
Roll dough into 12 equal dough balls. Drop 6 per sheet, spaced evenly.
Press three mini eggs on top of each cookie.
Bake 9-10 minutes, rotating pans halfway through, until the edges are slightly golden in color. Allow to cool completely before transferring.
Notes
Tips
Chop the Cadbury Mini Eggs to about the size of a chocolate chip.
Fully cream the butter and sugars - this aerates the mixture to create rise.
Once the flour has been added, just mix until the dry ingredients are incorporated, because overmixing the flour will start to develop the gluten and make the cookies tough.
How to Store
Room Temperature - Allow cookies to cool to room temperature then store in an airtight container for up to one week.
Refrigerator - Store in the refrigerator using the same method as room temperature - One week in an airtight container.
Freezer - Let cookies cool, then place in an airtight container, using parchment or wax paper between layers. Freeze for up to 3 months. Let thaw to room temperature when ready to eat.
Freeze Dough - Make cookie dough ahead of time. Roll into balls and freeze. When ready to use, bake from frozen state, but add a few extra minutes.