1-First, beat the softened unsalted butter, granulated sugar, and lemon zest together until light and fluffy, which takes about 3 minutes, then add the egg yolk and vanilla extract and mix until combined.

2-Next, whisk together the all-purpose flour, almond flour, and fine sea salt, then add this mixture to the butter blend and stir just until it forms a dough without over-beating.

3-Divide the dough in half, shape each portion into a disc, wrap it in plastic wrap, and refrigerate for about 1 hour until firm.

4-After chilling, remove the dough and let it soften for 5-10 minutes until it’s rollable but still cold.

5-On a floured surface, roll one disc to about 1/8-inch thickness and use a 2 1/2-inch round cookie cutter to cut out the cookies, transferring them to a parchment-lined baking sheet; re-roll scraps as needed, chilling the dough if it gets sticky.

6-Chill the cut cookies in the refrigerator for 30 minutes while preheating your oven to 350°F.

7-From the second disc, cut out 15 rounds and use a small cookie cutter or the end of a piping tip to remove centers for the top cookies, then chill these for another 30 minutes.

8-Bake all cookies for 12-15 minutes until the edges are lightly browned, then cool them on the pan for 5 minutes before moving to a wire rack.

9-Once fully cooled, sift confectioners’ sugar over the cookies with holes and spread about 1/2 teaspoon of raspberry jam or lemon curd on the flat side of each solid cookie, topping with a sugar-dusted cookie to form sandwiches.