Raspberry Linzer Heart Cookies (no nuts)

• 16 tablespoons (2 sticks) unsalted butter, at room temperature
• 2/3 cup plus 3 Tbsp. confectioners' sugar
• 1 large egg yolk 
• 1 teaspoon vanilla extract
• 2 1/2 cups all-purpose flour
• 1/4 teaspoon salt
• 2/3 cup seedless raspberry jam 
• 
  
• Preheat oven to 325°F; line 2 baking sheets with parchment. Beat butter and 2/3 cup sugar until fluffy. Beat in egg yolk and vanilla, then flour and salt. Shape dough into 2 disks; wrap 1 in plastic and refrigerate.
• On a floured surface, roll out remaining disk to about a 1/8-inch thickness. Cut out cookies with a 2 1/2-inch heart-shaped cutter. Use a smaller heart cutter to cut a window out of half of cookies. With a spatula, carefully transfer cookies to prepared baking sheets. Repeat with remaining dough. Gather scraps and roll out again to make more cookies.
• Bake cookies in batches until edges of cookies are just golden, 10 to 12 minutes. Let cool for 5 minutes, then transfer cookies onto wire racks to let cool completely.
• Spread 3/4 tsp. jam over flat side of each cookie that doesn't have a window. Top with remaining cookies, flat side down, so that jam shows through windows. 
• *Note, you can also dust the cookies with confectioners sugar. Before sandwiching the cookies together, lay the cookies with the windows out. Carefully sift 3 Tbsp. confectioners' sugar over cookies. Then sandwich the window cookies on top of the jam. (I skipped this part. I figured there was enough sugar in the cookies.)