These beautiful (and yummy!) sandwich cookies are the perfect way to say "be mine." Personalize them with your little Valentine's initials for a thoughtful touch they'll love.
Mix flour, baking powder and salt; set aside.
Beat butter and sugar using an electric mixer on medium speed until creamy (about 3-4 minutes). Scrape down sides of bowl.
Beat in vanilla, then yolks one at a time on medium speed until blended.
Gather dough into a ball; divide in half. Flatten each half into a disk and wrap separately in wax paper.
Refrigerate for at least an hour (this can be done the day prior to eating). Preheat oven to 350 degrees. Lightly grease baking sheets.
On a lightly floured surface, roll out a disk of dough about 1/4" thick. Use round cookie cutters to cut the shapes of the cookies.
On half of the unbaked cookies, cut out a shape in the centers using either a small heart-shaped cutter or letter-shaped cutters. Transfer to baking sheets.
Bake until golden around the edges (about 8-10 minutes). Transfer to baking racks and let cool.
Spread jam on bottom half of cookies. Top with cookies that have cutouts, bottom side down. Dust tops with powdered sugar.