In a food processor, pulse flour, salt, and sugar until combined. Add butter and pulse until mixture resembles coarse crumbs. Add 4 tablespoons of water; process just until dough forms.

If dough doesn't form, add remaining 1 tablespoon of water.

Divide dough in half. Shape each half into 5-inch round disks. Cover disks tightly with plastic wrap and chill for 1 hour.

Line a rimmed baking sheet with parchment paper. Unwrap 1 dough disk. On a lightly floured surface, roll out dough to 1/4-inch thick. Use a large heart-shaped cookie cutter to cut dough. Transfer hearts to the baking sheet.

Spoon and spread a scant tablespoon of jam on top of each heart, leaving a 1/2-inch border around edges. Unwrap the second dough disk, roll out, and cut into hearts. Place hearts on top of jam-topped hearts on the baking sheet.

Gently press seams with fingers to seal. Use fork tines to seal seams, then poke the top of each heart 3 to 4 times.

Cover hearts with plastic wrap and freeze for 2 hours or up to 1 week.

Heat oven to 375 degrees F. Uncover hearts and bake for 20 to 25 minutes until the crust is baked through and lightly golden.

Cool completely before icing.

To make icing, mix powdered sugar with 1 tablespoon of milk and vanilla. Add remaining tablespoon of milk if needed to make smooth but thick icing.

Spread icing over fully cooled hearts, leaving a 1/2-inch border around edges. Top with red and pink sprinkles if desired. Let icing set at room temperature.