Preheat the oven to 350°F and place your oven racks in the center of the oven.
In a medium sized bowl, sift or whisk the all-purpose flour, almond flour, and salt together.
9 ounces (255 grams or 2 cups) bleached all-purpose flour, 3 ounces (85 grams or ⅞ cup) almond flour, ¼ teaspoon salt
In another medium sized mixing bowl or bowl of your stand mixer, cream the sugar, and butter on medium speed just until it's well mixed. You don't want to beat shortbread cookies until "light and creamy" because the incorporated air will cause your cookies to puff.
8 ounces (227 grams or 2 sticks) unsalted butter, softened, 4 ounces (113 grams or ½ cup plus 1 tablespoon) granulated sugar
Add the almond extract and mix for one minute.
1 teaspoon almond extract
Add the flours and salt and mix for another minute. The dough may or may not clump together.
Pour out the mixture onto a sheet of plastic wrap and knead gently until the dough just starts to come together. Once it does, put it into the refrigerator for 15 to 30 minutes.
Divide the dough in half and re-wrap one half in plastic and leave it in the refrigerator while you are rolling out the other.
Roll out the dough to about ¼" to ⅓", and cut it into rounds or other shapes. For half of the rounds, use a smaller cookie cutter to cut out the center window.
Place cookies on a cookie sheet lined with parchment paper or silicone mat. They do not need much spacing, but do not crowd them. Re-roll scraps until you have used up all of the dough, returning the dough to the refrigerator as needed if it starts to warm and become difficult to roll and cut.
Place the cookie sheets in the freezer for about 10 to 15 minutes before baking. I usually freeze the first one while I am rolling out cookies for the second sheet and then bake the first sheet while the second one is in the freezer.
Bake for about 16 to 20 minutes, depending on the thickness of your cookies, until they feel slightly firm and the edges are just slightly brown. Small, thin cookies may start to brown before that. They will become firmer as they cool.
When the cookies are cool, warm up the jam in a small pot over low heat just to loosen it.
1 cup raspberry preserves
Hold a bottom cookie upside down in your hand and spoon one tablespoon of raspberry filling into the center. Spread the jam to about 1 centimeter from the edge of the cookie, keeping it slightly thicker in the center.
Add the top cookie right side up and press the cookies together gently. Set aside while you form all of the Linzer cookies.
Dust the cookies with the confectioners' sugar.
¼ cup confectioners' sugar
Linzer cookies are best the day that you make them, but you can store them in an air-tight container at room temperature for about one week.