01 - Preheat the oven to 350°F. Line a baking sheet with parchment paper.
02 - In a medium bowl, whisk together the almond flour, gluten-free all-purpose flour, sugar, salt, and baking powder until evenly distributed.
03 - In a separate bowl, whisk the egg, melted coconut oil or butter, lemon juice, lemon zest, and vanilla extract until smooth and well combined.
04 - Pour the wet mixture into the dry ingredients and stir until a soft, cohesive dough forms.
05 - In a small bowl, toss the sliced almonds with sugar, melted butter, and lemon zest until the almonds are evenly coated.
06 - Scoop tablespoon-sized mounds of dough onto the prepared baking sheet, spacing them about 2 inches apart. Gently flatten each portion with your fingers.
07 - Sprinkle a generous pinch of the almond crumble topping over each cookie, pressing lightly so the topping adheres to the surface.
08 - Bake for 13 to 15 minutes, or until the edges are golden and the tops feel set.
09 - Let the cookies rest on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely.