In a stand mixer, cream together room temperature unsalted butter, granulated sugar, and brown sugar until the mixture is light and fluffy, about 5 minutes. Add the large eggs one at a time, beating well after each addition, then mix in the vanilla extract until fully incorporated.

In a separate bowl, sift together the all-purpose flour, cornstarch, baking soda, baking powder, and salt. Gradually incorporate this dry mixture into the wet ingredients in the mixer on low speed, mixing until just combined.

Once your dough comes together, gently fold in the semi-sweet chocolate chips and Easter sprinkles using a spatula. Be careful not to overmix.

Using a 4 oz scoop, portion out the dough and flatten each scoop slightly. Place a Peep in the center of each flattened dough, encasing it completely by folding the dough around it, and form a ball.

Refrigerate the stuffed dough balls for at least 2 hours, or up to 48 hours if you want to plan ahead.

Preheat your oven to 375°F (190°C) while the dough chills. Line baking sheets with parchment paper. When ready, place 4 dough balls on each sheet. Bake for 14-16 minutes, until edges are golden brown.

Allow the cookies to cool on the baking sheets for 20-30 minutes.