Heat your oven to 350°F/180°C. Line three baking sheets with parchment paper. Once you have prepped your ingredients, keep ¼ cup of chocolate chips and ¼ cup of mini eggs to the side.
In a small saucepan over medium-low heat, melt the butter. Once melted, increase the heat to medium and let the butter begin to foam. Keep cooking and stirring with a spatula, until the butter begins to brown and gives off a nutty smell (2-3 minutes). Pour into the bowl of a stand mixer, making sure you scrape out all of the brown butter stuck at the bottom of the pan. Let cool.
Add the sugars, salt, vanilla baking soda, and baking powder to the stand mixer and beat with the paddle attachment. Beat for about 5 minutes until it is light and fluffy. Add the egg + yolk, and beat until the batter is smooth
Add in the flour and beat until smooth, but don’t overmix. Fold in the mini eggs, and chocolate chips.
Form the dough into balls (about 2 tablespoon each), 32 and place on your baking sheet, leaving at least 2 inches between them. Press the remaining mini eggs and chocolate chips on top of each cookie. Bake for 10-12 minutes for soft cookies, a minute or two longer if you want them crispier.
I recommend putting the mini eggs into a ziplock bag, and smashing them with a rolling pin rather than chopping them with a knife.