2 3/4 cups all-purpose flour, divided
1 tsp baking powder
3/4 tsp salt
2/3 cup unsalted butter, at room temperature
1 cup granulated sugar
2 tsp vanilla
3/4 cup seedless raspberry jam
Stir flour with baking powder and salt in a large bowl.
In another large bowl, beat butter with sugar on medium-high using an electric mixer, until fluffy, 3 min. Beat in eggs, 1 at a time, scraping down sides of bowl as needed. Beat in vanilla.
Using a wooden spoon, gradually stir in flour mixture, just until evenly blended.
Form into a ball. Divide dough in half. Shape each half into a flat disc. Wrap separately with plastic wrap. Refrigerate until firm, at least 1 hour or up to 1 week.
Preheat oven to 375F. Line 2 baking sheets with parchment paper.
Dust a rolling pin with flour. Roll dough no thicker than 1/4 in. on a lightly floured surface. Cut out shapes with a 2- to 3-in. heart cookie cutter.
Transfer to prepared baking sheets and place about 2 in. apart. Use a smaller cutter to cut out centres of half of the cookies on baking sheet.
Bake one sheet in centre of oven until cookies are pale golden, 7 to 8 min. Place cookie sheet on a rack for 5 min. Then remove cookies to a rack to cool completely.
Repeat with remaining dough. Gather dough scraps and form into a disc. Chill until firm enough to re-roll.
Assemble cookies by generously dusting cut-out cookies with icing sugar. Spread about 1 tsp jam on each bottom half. Then set sugar-dusted cookies over jam-covered hearts.
Store cookies in an airtight container at room temperature up to 1 week or freeze up to 1 month.