Makes about 3 1/2 dozen.
2 cups all-purpose flour
1/2 cup Dutch cocoa powder
1/2 teaspoon baking powder
1/2 teaspoon baking soda
8 tablespoons (1 stick) unsalted butter
1/2 cup pure vegetable shortening
1/2 cup granulated sugar
1 1/4 cups light-brown sugar, firmly packed
2 large eggs
1 teaspoon pure vanilla extract
1 cup semisweet chocolate chips
1/2 cup peanut butter
Sift together flour, cocoa powder, baking powder, and baking soda. Set aside.
In the bowl of an electric mixer fitted with the paddle attachment, beat butter, shortening, granulated sugar, and 1 cup light-brown sugar on medium speed until light and fluffy, about 2 minutes. Add eggs, one at a time, mixing until fully combined between each addition. Add vanilla, and beat to combine. Gradually add dry ingredients, and mix on low speed until fully combined. Remove from mixer. Using a wooden spoon, stir in chocolate chips. Cover bowl with plastic wrap, and chill until firm, about 1 hour.
Preheat the oven to 350 degrees. Line baking sheets with Silpats or parchment paper.
In a small bowl, using a rubber spatula, stir together peanut butter and remaining 1/4 cup light-brown sugar.
Using a 1 1/4-inch scoop or heaping tablespoon, drop dough onto prepared baking sheets about 2 inches apart. Make a thumbprint in the center of each cookie. Fill thumbprint with 1 teaspoon peanut-butter mixture. Top with a second scoop of dough, and carefully mold dough to cover “surprise.”
Bake until firm, about 12 minutes. Transfer sheets to wire racks to cool for 5 minutes, then transfer cookies to racks.