Chocolate Mint Thumbprints

Name: Chocolate Mint Thumbprints
Ingredients: For the chocolate mint thumbprints:; 2 ounces good-quality dark chocolate (60 to 72%); 2 ounces mint chocolate (or Andes mint chocolate candies); 1 1/2 cups all-purpose flour; 1/2 cup dark unsweetened cocoa powder (like Valrhona); 3/4 teaspoon salt; 1 cup (2 sticks) unsalted butter, cut into 1-inch cubes, at room temperature; 1⁄3 cup granulated sugar; 2 tablespoons firmly packed dark brown sugar; 2 large egg yolks; 1 teaspoon pure vanilla extract; 1 cup coarse sugar for rolling; For the white chocolate filling:; 3 ounces good-quality white chocolate, coarsely chopped; 3 tablespoons heavy cream; 1/2 teaspoon pure peppermint extract