Preheat the oven to 350 degrees Fahrenheit.
In a large bowl combine butter and sugars. Beat on low with an electric hand mixer or stand mixer until smooth and creamy. Gradually add eggs, vanilla. Mix on low until combined. Set aside.
In a separate bowl, combine dry ingredients. Whisk to combine and add to wet ingredients gradually.
Add the dry ingredients in batches, about ½ or 1 cup at a time, beat on low until combined, and then continue with the next batch.
Mix until ingredients are almost combined, a few lumps here and it is fine.
In a zip lock bag crush the mini eggs into smaller pieces or chunks.
Stir the mini eggs and chocolate chunks or chips into batter. The batter will be on the softer side and sticky, freeze it for 30 or more minutes until you can form balls (not very frozen though). Chill between the batches too for less spreading and uniform cookies.
Scoop about 1 ½ tablespoonfuls of dough, rolling them into about balls.
Arrange the cookie balls on a baking sheet lined with parchment paper at least 3 inches apart. Don’t press down!
Bake for 10-12 minutes (the time varies due to different ovens). While cookies are hot, decorate them with more mini eggs and chocolate chips (optional). PRO TIP. To make perfectly round cookies: while cookies are hot and still on the baking sheet, take a small bowl, rounded glass, or a mug, and swirl multiple times over still-warm cookies. Do it until they are nicely rounded and in uniform sizes.
The cookies will have a soft center inside. Once they cool down they will set well and the texture inside remains soft, and buttery.
Let the cookies stand in the pan for 5-10 minutes before transferring to a wire rack.