Raspberry Linzer Heart Cookies

Have a heart! This is a very cute heart-shaped cookie stuffed with raspberry jam and sprinkled with powdered sugar. Eat it with a cup of coffee or share it with someone you love.
Preheat oven to 325 °F; line 2 baking sheets with parchment. Whisk together the butter and 2/3 cup sugar until fluffy. Whisk together the egg yolk and vanilla, then the flour and salt. Form 2 circles from the dough; wrap 1 in clingfilm and put in the refrigerator.On a floured surface, roll out the remaining circle about 1/8 inch thick. Cut the cookies with a 2 1/2-inch-thick heart-shaped cookie cutter. Cut a window out of the cookie halves with a smaller heart mold. Using a spatula, carefully transfer the cookies to the prepared baking sheets. Repeat with the remaining dough. Collect the scraps and roll them out again to make more cookies.Bake the cookies in batches until the edges of the cookies are slightly golden, 10 to 12 minutes. Let cool for 5 minutes, then transfer the cookies to a wire rack to cool completely.Spread 3/4 teaspoon of jam on the flat side of each cookie without a window. Top with the remaining cookies, flat side down, so that the jam shines through the windows. Carefully sift 3 tablespoons. Sprinkle the cookies with sugar.