Preheat the oven to 350℉/180℃. Line two baking trays with parchment paper and set aside. Chop the mini eggs and set aside.
3/4 cups Mini Eggs
In a medium-sized pot over medium-high heat, melt the butter. Allow it to melt, then continue stirring as it foams, sizzles, crackles, and begins to brown. The butter will go from melted to a deep brown color with specks of brown butter forming at the bottom of the pot. This process will take 3-5 minutes total, a nutty aroma will begin to fill the air too. Don't stop mixing or else it can burn. Once done, transfer into a heat-safe glass to cool. Allow to cool for 15 minutes before using.
3/4 cups + 2 tbsps unsalted butter
In a bowl, add the flour, oats, baking soda, baking powder, cornstarch, and salt. Stir to combine and set aside.
1 1/2 cups all purpose flour, 2 cups rolled oats, 1 1/4 tsps baking soda, 1/2 tsp baking powder, 1/4 tsp salt, 1 tsp cornstarch
In another bowl, whisk together the brown butter, brown sugar, and white sugar.
1/2 cup dark brown sugar, 1/2 cup white sugar, 3/4 cups + 2 tbsps unsalted butter
Add in the eggs and vanilla and continue whisking, scraping the bowl as needed.
2 large eggs, 1 tbsp vanilla
Add in the dry ingredients. Gently fold together with a spatula until almost completely combined.
Mix in the chopped mini eggs.
3/4 cups Mini Eggs
Scoop the cookies onto a cookie tray (I scooped 6 per tray and used a 2 tbsp cookie scooper), spacing them evenly apart from one another. Gently flatten the cookies for better spreading. Add extra mini eggs on top if desired.
Bake for 13-16 minutes. The cookies are ready when the edges are a light golden brown and the middle is slightly puffy. Allow to cool, transfer to a cooling rack, and enjoy!