Mint Chocolate Chip Whoopie Pies

Ingredients

• For the cookies:
• 16 tablespoons unsalted butter
• 1 1/2 teaspoons salt
• 2 teaspoons peppermint extract
• 1 tablespoon baking powder
• 1 1/2 cups sugar
• 3 eggs
• 4 1/2 cups all-purpose flour
• 1 cup milk
• Green food coloring, to taste, optional
• 2 cups chocolate morsels
• For the filling:
• 4 cups chocolate chips
• 2 tablespoons light corn syrup
• 4 tablespoons unsalted butter
• 1 1/2 cups heavy cream
• 1/2 teaspoon peppermint extract

Directions

1. Set 2 oven racks in the center of the oven, then heat it to 400 degrees F. Prepare 2 baking sheets by greasing them lightly or covering them with parchment. In a large bowl, use a wooden spoon or an electric mixer to beat the butter with the salt, peppermint extract, baking powder, and sugar until the mixture looks pale and fluffy. Beat in the eggs one at a time, mixing thoroughly after each goes in. Mix in the flour and milk in alternating additions, starting with flour and finishing with flour. Add the green food coloring and fold it in gently, without overworking the batter. Stir in the chocolate chips last.
2. Scoop the dough onto the prepared sheets with an ice cream scoop, spacing the cookies 2 to 2 1/2 inches apart. A large 4 ounce scoop will make about 24 jumbo cookies, enough for 12 sandwiches, while a small 2 ounce scoop will make about 48 cookies, enough for 24 sandwiches.
3. Bake for about 11 minutes, just until the tops have barely set. Leave the cookies on the baking sheets for 5 minutes, then move them to a rack and let them cool all the way.
4. Put the chocolate chips, corn syrup, butter, and heavy cream in a large microwave-safe bowl. Microwave the mixture, pausing to stir every 30 seconds, until it is fully smooth, 2 to 3 minutes total. Stir in the peppermint extract. Refrigerate the filling, stirring now and then, until it reaches cool room temperature. Take it out of the refrigerator and beat it on high speed with an electric mixer until the color becomes lighter and the filling thickens a bit. If it has not lightened or thickened after several minutes of beating, refrigerate it for another 15 minutes, then beat it again. Spread a generous layer of filling over the flat side of a cookie, then top it with another cookie to make a pie. Repeat with the remaining pies. Serve, and store in an airtight container at room temperature for up to 5 days.