Preheat the oven to 350 degrees Fahrenheit. Line a baking sheet or two with parchment paper or a silicone liner.
Cream together the butter and sugars in a large bowl for about 3 minutes. 1 cup unsalted butter, 1 cup brown sugar, 3/4 cup granulated sugar
Add in the eggs and vanilla and stir into the creamed butter. 2 large eggs, 2 tsp vanilla
Add the dry ingredients (flour, baking soda, baking powder, cornstarch, and salt) to the wet ingredients and stir everything together till combined, and you have a nice soft cookie dough. 3 cups all purpose flour, 1 tsp baking soda, 1 tsp baking powder, 1 tsp cornstarch, 1 tsp salt
Add in 1 cup of the m&ms and chocolate chips and fold them evenly into the batter. 1 1/2 cup m&ms, 1 cup mini chocolate chips
Scoop the cookie dough into large 2 TBS sized cookie balls. Roll them into smooth balls.
Place cookie balls onto the prepared cookie sheet, at least 3 inches apart.
Bake the cookies for about 8-11 minutes, or until the edges just start to turn golden.
While the cookies are baking, use the remaining 1/2 cup of M&Ms, and pair up the m&ms by color, and cut half of them in half to create the bunny ears.
Remove the pan from the oven.
Place 1 whole M&M with the m&m logo face down into the top of the cookie. Add two M&M halves above it for bunny ears. Add another bunny or two on top. Then repeat with additional cookies.
Leave the cookies on the baking sheet for about 5 to 10 minutes to cool.
Remove cookies to cooling rack to cool completely, or enjoy after a few more minutes warm.