Begin by creaming together the unsalted butter, granulated sugar, and light brown sugar in a stand mixer on medium speed for 3–4 minutes. Add the eggs and vanilla extract, mixing until well combined. Gradually sift in the flour, baking soda, and salt, mixing just until incorporated. Gently fold in 2/3 of the chopped Mini Eggs and dark chocolate.

Scoop the dough into 2 cm balls using a cookie scoop or your hands, placing them on a parchment-lined baking tray. Cover and refrigerate for at least 1 hour or freeze for 30 minutes.

Preheat your oven to 350°F (175°C). Space the chilled cookie balls evenly on a new baking tray. Bake for 12–15 minutes. At 9 minutes, press the remaining Mini Egg pieces into the top of each cookie.

Remove the cookies when the edges begin to brown and the centers are still slightly jiggy. Cool on the tray for 10 minutes before transferring to a wire rack.