- 1 cup all-purpose flour, plus more for parchment
- 1/3 cup unsweetened Dutch-process cocoa powder
- 1 stick unsalted butter, room temperature
- 1/4 cup sugar
- 1 large egg
- 3/4 teaspoon pure vanilla extract
- 3 tablespoons heavy cream
- 1 cup apricot jam
- Sift flour, cocoa, and 3/4 teaspoon salt into a medium bowl. Beat butter and sugar with a mixer on medium speed until pale and fluffy, about 4 minutes. Beat in egg and vanilla. Reduce speed to low, and add flour mixture in 3 additions, alternating with heavy cream, beginning and ending with flour. Shape dough into a rectangle, and wrap in plastic wrap. Refrigerate for 30 minutes.
- Roll out dough between 2 sheets of lightly floured parchment to a 1/16-inch thickness. Refrigerate until firm, 15 to 20 minutes.
- Preheat oven to 350 degrees. Working in batches, line twenty-four 3-inch barquette molds (1/2 inch deep; surlatable.com) and twenty-four 2 1/4-inch round tartlet molds: Cut out dough 3/4 inch wider than each shape on all sides, fit inside mold, and trim excess by rolling a rolling pin over tops. Place a matching mold over dough in each tart shell and press down gently. Freeze until tart shells are firm, about 20 minutes.
- Bake tart shells on baking sheets for 15 minutes with top molds still in place. Remove top molds and bake until tart shells are cooked through, 7 to 10 minutes more. Let cool completely in molds set on wire racks. Remove tart shells from molds.
- Transfer jam to a disposable pastry bag and snip a 1/4-inch opening. Pipe about 1 teaspoon jam evenly into the bottom of each tart shell.
- Transfer ganache to another disposable pastry bag or a resealable plastic bag and snip a 1/4-inch opening. Fill each tart shell. Let stand until set, about 2 1/2 hours at room temperature or 1 hour in the refrigerator. (Refrigerating tarts will make ganache set faster but be less shiny.)
Tart dough can be refrigerated for up to 2 days. Tart shells can be baked and stored at room temperature for up to 1 day before filling.