In a bowl, whisk together flour, ground almonds, cinnamon, and salt. Set aside.
1 cup all-purpose flour, 1 cup finely ground almonds, ½ teaspoon ground cinnamon, ¼ teaspoon salt
In a large bowl, beat butter and sugar until light and fluffy (about 2 minutes). Add the egg yolk and vanilla. Mix until smooth.
½ cup unsalted butter, ½ cup granulated sugar, 1 large egg yolk, 1 teaspoon vanilla extract
Add dry ingredients and mix just until combined. Dough will be soft but not sticky.
Divide the dough into two, flatten into discs, wrap in plastic, and refrigerate at least 1 hour (or overnight).
Preheat oven to 350°F. Line two baking sheets with parchment paper.
Roll dough to about ⅛–¼ inch (3–5 mm) thick on a lightly floured surface.
For half the cookies, cut a small shape (heart, star, or circle) in the center. For the other half, cut flat rounds. These two will make the tops of your sandwich cookies.*If the weather is warm, place baking sheets in the freezer for 10 to 15 minutes before baking.
Place cookies on sheets and bake 8–10 minutes, until edges are lightly golden. Cool completely on wire racks.
Dust cut-out tops with powdered sugar.
Powdered sugar
Spread ~1 tsp raspberry jam on each solid base cookie. Gently sandwich with a sugar-dusted top.
½ cup raspberry jam