In a medium bowl, whisk together the flour, baking powder, 2 Tbsp confectioners’ sugar, cinnamon, and salt. Set aside.

In the bowl of a stand mixer fitted with the paddle attachment, add the softened butter and granulated sugar. Beat on medium speed until light and fluffy, 2–3 minutes.

Add the vanilla and egg. Beat until combined.

Reduce the mixer to low. Add the flour mixture and mix just until incorporated. Do not overmix.

Divide the dough in half. Shape each half into a disk. Wrap both disks in plastic wrap. Refrigerate for at least 2 hours.

Preheat the oven to 375°F. Line two baking sheets with parchment paper.

Working with one disk at a time, roll the dough on a lightly floured surface to 1/8-inch thickness.

Use a 2-inch fluted cookie cutter to cut rounds. For half the rounds, cut a 1/2-inch heart from the center to create windowed tops.

Re-roll scraps and cut more cookies as needed. Place cookies 2 inches apart on the prepared sheets.

Chill the cookie-lined baking sheets for 5 minutes.

Bake for 8–10 minutes, rotating pans 180° halfway through. Cookies should be pale golden at the edges.

Transfer pans to wire racks and allow cookies to cool completely on the pans.

Meanwhile, heat the strawberry jam in a small saucepan over medium heat. Simmer until slightly reduced and thickened, about 7 minutes. Let cool.

Dust the windowed (cutout) cookies with confectioners’ sugar.

Spread a thin layer of cooled jam onto the solid cookie bottoms. Top each with a dusted cutout cookie to make sandwiches.