• Unwrap the Cream Eggs. Place in a freezer bag and place in the freezer until ready to use.

Make the Dough

• In a large bowl, whisk together the flour, cornstarch, baking powder, baking soda and salt. Set aside.
• In a separate large bowl, cream together the butter, brown sugar and granulated sugar until creamed.
• Beat the eggs and vanilla into the butter mixture. Turn off the mixer and scrape down the bottom and sides of the bowl a few times to ensure there are no lumps of butter stuck to the bowl.
• With the mixer on a low speed, mix in the dry ingredients about ½ at a time until incorporated. Turn off the mixer. Squeeze the dough between your fingers. If the dough sticks to your fingers, mix in 1-2 extra tablespoons of flour.
• Mix in the chocolate chips. The dough should be thick.
• Cover the bowl with plastic and refrigerate for at least 1 hour or up to 48 hours.

Assemble the Dough Balls

• Take the dough out of the fridge. If it's been in the fridge overnight, let it sit on the counter for 5-10 minutes before forming into balls.
• Scoop out about 3 tablespoons of dough (about 3 to 3½ ounces or 85-100 grams). Flatten slightly into a round disc shape and press the edges up to create a nest shape.
• Place an unwrapped, frozen Cream Egg in the middle of the cookie dough. Place the Cream Egg horizontal.
• Scoop out another 1 tablespoon or so (about 1 ounce or 25 grams) of dough. Flatten into a round shape and place on top of the frozen Cream Egg.
• Pinch the edges of the dough around the Cream Egg so that it's entirely covered in dough. Roll the dough into ball, ensuring that the Cream Egg remains horizontal.
• Freeze the dough balls for at least 2 hours or up to 2 months. If baking that day, dough balls can be placed on a plate and covered with plastic wrap to freeze. If freezing for an extended period, place in a freezer bag.

Bake

• When ready to bake, preheat the oven to 375℉ (190℃). Line cookie sheets with parchment paper or silicone baking mats.
• Place frozen cookie dough balls at least 2½ inches (about 6 cm) apart on the lined cookie sheets. Do not thaw.
• Bake 1 cookie sheet at a time in the middle of the preheated oven. The cookies will need about 14-16 minutes, or until the tops look just set. (Keep remaining cookie dough balls in the freezer while the first sheet is baking to ensure that the frozen cookies do not start to thaw).
• Cool the cookies on the cookie sheets. For perfectly round cookies, use a round biscuit cutter or mug (larger than the cookies in size) and place around the edges of the warm, fresh from the oven cookie. Gently mold each cookie into a round shape by drawing a circle with the biscuit cutter. Note: You aren't cutting the cookie into a circle. You want to gently press the sides to create a circular shape.