Heat oven to 350°F. Grease a standard muffin tin or line with paper cups.
Whisk flour, sugar, and salt in a large bowl.
Cut in the cold butter until the mixture looks like coarse crumbs with pea-sized bits.
Stir in vanilla and lemon zest. Drizzle in ice water, mixing just until the dough holds together.
Flatten into a disc, wrap, and chill 10 minutes to relax the dough.
Roll dough to about 1/8 inch thick. Cut 3-inch rounds and nestle into muffin cups to form shells.
Spoon 1 to 1 1/2 tablespoons jam into each shell. Do not overfill.
Brush exposed crust with heavy cream. Add small dough cutouts on top if you like.
Bake 20 to 22 minutes, until edges are golden and the jam bubbles gently.
Cool 10 minutes in the pan, then transfer to a rack. Dust with confectioners' sugar before serving.