Preheat the oven to 350° Fahrenheit. Line a large pan with parchment paper or your favorite baking mat.
Brown your butter. To do this, place the butter in a small pan over medium low heat. Let this go for a few minutes, or until it reaches a deep amber hue. You’ll see it slowly start to brown throughout this process. When it's done, remove it from heat and set it aside to cool.
While the butter cools, add the flour, baking soda, and salt to a medium sized bowl and whisk to combine. Now is also a good time to chop half the Cadbury Mini Eggs. Set these to the side once you're done.
Cream together the brown butter and sugar. I like to use a stand mixer for this, but using a hand mixer or whisk will work, too. Add in one egg, plus the yolk of another egg, and the vanilla extract.
Add the flour mixture to the wet one and mix just until combined, being careful not to overmix.
Fold in the chopped Cadbury Mini Eggs and scoop dough into balls (I used a medium sized cookie scoop, which is equivelant to about 3 tbsp). Press a couple of the remaining Cadbury Mini Eggs into each of the dough balls for a super cute and festive look.
Place 6-9 cookies equidistant on your lined pan (depending on the size of the pan) and bake for 12-14 minutes. They'll still seem a bit raw when you pull them out but that's perfectly fine! When you take them out, slam them down onto your stove or counter top to knock the air out of them. Let cool for a few minutes before transferring to a cooling rack. Repeat with the rest of the dough until it's all gone!