In small bowl, mix flour and salt.
In medium-size bowl, beat together sugar, butter, sour cream, egg yolk and vanilla until creamy and smooth, about 2 minutes. Stir in flour mixture. Shape into disk; wrap in plastic wrap; refrigerate several hours or overnight.
Heat oven to 350°F. Lightly grease 2 baking sheets.
Roll out dough on lightly floured surface to 3/8-inch thickness. Cut into rounds with 2-1/2-inch-round cookie cutter. Place 1/2 teaspoon raspberry-chocolate bits in center of each. Moisten edges of rounds; fold in half; press edges together. Place on prepared baking sheets.
Bake in 350°F oven for 10 to 12 minutes or until lightly browned at edges. Transfer cookies to wire rack; let cool.
Melt disks following directions. Drizzle over cookies. Store airtight at room temperature for 1 week. Makes 32 cookies.
Chocolate coating disks available from Wilton, www.wilton.com.