Preheat oven to 325°F. Line a cookie sheet with parchment paper.
In a large bowl, whisk cooled melted butter, brown sugar, and sugar. Add in vanilla and egg. Whisk until smooth.
1/4 cup butter, 1/3 cup light brown sugar, 1 tbsp white sugar, 1 egg yolk, 1 tbsp vanilla
Add in flour, baking soda, and salt. Use a rubber spatula and fold the dough until just combined. Do not over mix! Add in chopped mini eggs and fold into dough.
2/3 cups all-purpose flour, 1/4 tsp baking soda, 1/4 tsp salt, 1/2 cup Cadbury mini eggs
Scoop 6 cookie dough balls and place on the prepared cookie sheet.
Bake for 13-16 minutes. Mine took 16 minutes. The cookies will be ready when the edges are a golden brown, but the inside will look very soft. Remove from oven and add a few more mini eggs on top if desired. Let the cookies cool on the hot pan for a few minutes before serving warm or cool completely and enjoy!