Combine flour, baking soda, and baking powder, and mix well.
Using either an electric mixer or by hand, cream the butter and both sugars, then add vanilla and eggs, mixing well.
Add dry ingredients to wet, and mix to combine.
Crush your mini eggs either in a food processor, or by putting them into a Ziploc bag and smashing them with a meat tenderizer, or a rolling pin. Divide crushed mini eggs in half and add half to cookie dough, then mix.
Use a 1 tbsp cookie scoop to form cookies and place on baking sheet, and flatten slightly.
Bake for 8-10 minutes, until edges are golden, and let cool.
Mini Egg Buttercream Icing
Combine butter, vanilla, and shortening with electric mixer.
Mix in icing sugar, one cup at a time.
Add in milk a splash at a time until icing is your desired consistency.
->Optional: If you want colored icing add in your food coloring now.
Add remaining crushed mini eggs to icing, and mix.
Mini Egg Cookie Sandwiches
Flip half of your cookies so that they are bottom side up.
Add icing onto bottom of cookies either by spreading, or piping it on.
Put remaining cookies on top of icing, bottoms down.