1. Cream It Up: In a large mixing bowl, gently beat the softened butter with the maple syrup (or coconut sugar) until the mixture is light and fluffy. This usually takes about 2-3 minutes.
2. Wet Ingredients: Stir in the large egg, vanilla extract, and fresh lemon zest until everything is well combined.
3. Dry Mix: In a separate bowl, whisk together the whole wheat pastry flour, almond flour, baking powder, and sea salt. Make sure there are no lumps.
4. Combine: Gradually add the dry flour mixture to the wet butter mixture, mixing on low speed or by hand until a soft dough forms. Don't overmix, just until combined.
5. Chill Out: Divide the dough into two equal portions, flatten each into a disk, wrap them in plastic wrap, and refrigerate for at least 1 hour. This makes the dough much easier to handle.
6. Roll & Cut: Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper. On a lightly floured surface, roll out one disk of chilled dough to about 1/8-inch thickness. Use a Linzer cookie cutter (or two different-sized round cutters) to cut out shapes. For half of your cookies, cut out a small center from the middle. Repeat with the second dough disk.
7. Bake: Carefully transfer the cut-out cookies to your prepared baking sheet. Bake for 10-12 minutes, or until the edges are just lightly golden.
8. Cool Down: Let the cookies cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely.
9. Assemble: Once cooled, spread a small dollop (about 1 teaspoon) of all-fruit jam onto the flat bottom of each whole cookie. Place a cookie with the cut-out center on top, gently pressing down.
10. Dust (Optional): If you like, lightly dust the assembled cookies with powdered erythritol or powdered sugar for that classic Linzer look.