Mini Chocolate Tarts with Pistachio Halvah and Sesame Salt

Name: Mini Chocolate Tarts with Pistachio Halvah and Sesame Salt
Ingredients: 1 1/4 cups all-purpose flour; 1/4 cup natural unsweetened cocoa powder; of kosher salt; 1/4 cup plus 1 Tbsp. powdered sugar; 1/2 cup (1 stick) unsalted butter, room temperature; 1 large egg yolk; 3/4 teaspoon vanilla extract; Nonstick vegetable oil spray; 3 ounces bittersweet chocolate (do not exceed 70% cacao), chopped; 3 ounces high-quality milk chocolate, chopped; 3/4 cup heavy cream; 2 ounces pistachio halvah, crumbled; 1 tablespoon sesame seeds; 1/4 teaspoon flaky sea salt, such as Maldon