If you’re using whole almonds, toast them first. Spread them on a baking sheet and bake at 350°F (175°C) for about 8–10 minutes, until golden and fragrant. Let them cool, then grind finely in a food processor.
In a large mixing bowl, beat the softened butter and sugar together until light and fluffy — about 2–3 minutes.
Add the egg yolk and vanilla extract, then beat again until smooth.
In another bowl, whisk together the flour, ground almonds, salt, and cinnamon (if using). Gradually add this mixture to the butter mixture, stirring until everything just comes together.
The dough will be soft but not sticky. If it feels too soft, refrigerate it for 10–15 minutes before rolling.
Place the dough between two sheets of parchment paper and roll it out to about ¼ inch thick.
Transfer the rolled dough (still between the parchment) to a baking sheet and refrigerate for 30 minutes. Chilling helps the cookies hold their shape when baked.
Once chilled, use a round or fluted cookie cutter (about 2 inches wide) to cut out shapes. For half of them, use a small cutter (like a heart or circle) to cut out the centers — these will be the tops.
Gather the scraps, reroll, and continue cutting until all the dough is used.
Place the cookies about an inch apart and bake for 10–12 minutes, or until the edges are lightly golden.
Let them cool completely on a wire rack before assembling
Spread about ½ teaspoon of jam on the flat side of each solid cookie. Be gentle — you want just enough to hold but not too much that it seeps out the sides.
Dust the cutout tops with powdered sugar, then carefully sandwich them on top.
