If using full-size low-sugar sandwich cookies, place them in a zip-top bag and crush with a rolling pin or pulse 6–8 times in a food processor until you have mostly small pieces and some fine crumbs. Reserve 2 tablespoons of the finest crumbs for sprinkling, and set the rest aside for folding into the dough.

Soften butter to room temperature (soft enough to press but not melted). If using powdered erythritol for icing, have it ready.

Make the cookie dough

Cream butter and sweetener

In a large bowl, beat the softened butter with the granulated erythritol (or monk fruit blend) until light and slightly fluffy, about 1–2 minutes using a hand mixer or 3 minutes by hand with a spatula.

Add egg and vanilla

Beat in the egg and vanilla extract until fully incorporated, scraping down the bowl as needed.

Combine dry ingredients

In a separate bowl, whisk together the almond flour, coconut flour, unsweetened cocoa powder, baking powder, and sea salt until evenly distributed.

Gradually add the dry ingredients to the wet mixture, stirring until a cohesive dough forms. The dough should be soft but hold its shape; if too dry, add 1–2 teaspoons water or heavy cream; if too sticky, sprinkle in 1 tablespoon additional almond flour.

Fold in the crushed low-sugar cookies and shredded coconut (if using) until distributed evenly. Reserve a few slightly larger cookie pieces for pressing on top of each cookie before baking.

Shape and bake

Portion dough using a tablespoon or small cookie scoop (about 1 tablespoon each) onto the prepared baking sheet, spacing cookies 1.5–2 inches apart. You should get about 18–22 small cookies.

Gently press the top of each cookie with your fingers to flatten slightly and press a reserved cookie piece into the center of a few cookies for the cookies-and-cream look.

Bake in the preheated oven for 10–12 minutes, until edges are set and the centers are slightly soft. Rotate the pan once halfway through baking for even color.

Remove from oven and let cookies cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely. They will firm up as they cool.

Optional finishing & icing

For a simple low-sugar icing, combine powdered erythritol (if using) with 1 teaspoon water or heavy cream in a small bowl and whisk until smooth. Drizzle over cooled cookies with a spoon. Alternatively, use the melted zero-sugar dark chocolate to drizzle for a richer finish.

Sprinkle a tiny pinch of coarse sea salt on top of drizzled cookies to enhance flavor. Allow any drizzle to set (10–15 minutes) before storing.

Storage

Store cooled cookies in an airtight container at room temperature for up to 4 days, or refrigerate up to 10 days. For longer storage, freeze in a single layer on a tray until solid, then transfer to a freezer bag for up to 3 months. Thaw at room temperature before serving.