Cream the butter and sugars: In a large mixing bowl, beat 1 Cup softened butter with 1/2 Cup granulated sugar, 1/2 teaspoon cinnamon and 3 Tablespoons brown sugar until light and fluffy, about 2–3 minutes. Don’t rush this step .. fluffy butter equals tender cookies.
Add flavor builders: Mix in 2 Teaspoons vanilla extract and 2/3 cup almond flour.
Add dry ingredients: In a separate bowl, whisk together 2 cups all purpose flour, 1 tablespoon cornstarch, and 1/2 teaspoon salt. Gradually stir into butter mixture until combined (don’t over-mix, but make sure dough is completely combined).
Chill the dough: Form the dough into a disk, wrap tightly or add to a large zip top bag, and refrigerate for at least 1 hour. This step is non-negotiable. It firms the butter so the cookies hold their shape.
Preheat and prep: Heat oven to 350 degrees Fahrenheit. Line two baking sheets with parchment paper.
Roll the dough (secret weapon time): Place the chilled dough on a clean countertop or a large cutting board (glass boards seem to work best for me) with a sprinkling of flour to keep the dough from sticking. Put a sheet of parchment paper on top of the dough and roll it out underneath the parchment. No sticking. No flour storm. No drama. Roll about 1/4 inch thick - thick enough to survive baking and sandwiching.
Cut shapes: Cut solid shapes for the bottoms and matching shapes with a small center cut-out for the tops. Hearts are the easiest (in my opinion) and hold their shape beautifully. Transfer to prepared baking sheets.
Bake: Bake at 350 degrees for 9–10 minutes, just until the edges are lightly golden. Do not overbake. They should look set but pale in the center.
Cool completely: Let cookies rest on the baking sheet for 5 minutes, then transfer to a rack. They must be fully cool before assembling.
Dust and fill: Using a sifter, lightly dust the cut-out tops with powdered sugar. Spread about 1 Teaspoon raspberry jam onto each bottom cookie, then gently press the sugared tops over the jam to create your classic raspberry sandwich cookie.