The classic whoopie pie is a cake-like chocolate cookie with creamy white filling. These pies flip-flop that traditional formula, sandwiching two vanilla cookies around rich chocolate filling. Add even more chocolate by adding semisweet chips to the cookies.

Cookies
1 cup (2 sticks 8 ounces) unsalted butter
1 1/2 teaspoons salt
2 teaspoons vanilla extract
1 tablespoon baking powder
1 1/2 cups (10 1/2 ounces) sugar
3 large eggs
4 1/2 cups (19 ounces) King Arthur Unbleached All-Purpose Flour
1 cup (8 ounces) milk
2 cups (12 ounces) chocolate chips, optional

Chocolate Filling
4 cups (24 ounces) semisweet chocolate chips
2 tablespoons (3/4 ounce) light corn syrup
4 tablespoons (1/2 stick, 2 ounces) unsalted butter
1 1/2 cups (12 ounces) heavy cream

Preheat the oven to 400°F. Lightly grease (or line with parchment) two baking sheets.

To make the cookies: In a large mixing bowl, cream together the butter, salt, vanilla, baking powder, and sugar. Add the eggs one at a time, beating well after each addition. Add the flour to the wet ingredients alternately with the milk, beginning and ending with the flour. Do this gently; there’s no need to beat the batter. Stir in the chocolate chips at the end.

Using a muffin scoop, or a 1/4-cup measure, drop the dough onto the prepared baking sheets. Wet your fingers, and flatten and smooth each mound of dough to a circle about 3" across. Leave 2 to 2 1/2 inches between each cookie, for expansion.

Bake the cookies for 11 minutes, or until they’re barely set on top; they won’t have colored at all. Cool them on the pan for 5 minutes, then transfer to a rack to cool completely.

To make the filling: Place the chocolate chips, corn syrup, butter, and heavy cream into a large microwave-safe bowl. Heat in the microwave for 2 to 3 minutes, until the mixture is very hot. Stir until the chocolate melts and the mixture is smooth. Chill in the refrigerator, stirring occasionally, till the filling is cool room temperature. Remove from the fridge, and beat at high speed with an electric mixer until it lightens in color and thickens slightly. If the filling doesn’t lighten and thicken after several minutes of beating, chill for another 15 minutes, then beat again. Spread about 1/3 cup filling per cookie on half the cookies (it will feel like you’re piling it on; that’s precisely the point!). Work quickly, as the filling will start to harden. Sandwich the remaining cookies atop the filled ones. For best storage, wrap each pie individually in plastic wrap, and store at room temperature.
Yield: 12 whoopie pies without chocolate chips, 13 whoopie pies with chips.