Prep the oven and pan. Preheat to 325°F (163°C). Line a baking sheet with parchment paper for easy release and even baking.

Cream the butter and sweetener. In a medium bowl, beat the softened butter and powdered sweetener with a hand mixer for 1–2 minutes until light and fluffy. Mix in vanilla (and almond extract, if using).

Add dry ingredients. Sprinkle in salt, then add almond flour in two additions. Mix on low just until a soft dough forms. If adding zest, fold it in now.

Chill the dough. Shape the dough into a log or flatten into a disc, wrap, and chill for 20–30 minutes. This step keeps the cookies from spreading.

Shape the cookies. For rounds, slice the chilled log into 1/3-inch thick discs. For cut-outs, roll the disc between two parchment sheets to about 1/3 inch and cut with a small cookie cutter. Gently transfer to the baking sheet.

Optional finish. Lightly poke each cookie once or twice with a fork for a classic shortbread look. Dust the tops with a tiny pinch of powdered sweetener if you want a sweeter finish.

Bake. Bake for 10–14 minutes, until the edges are just turning golden and the centers look set. Do not overbake; they will firm up as they cool.

Cool completely. Let cookies cool on the sheet for 10 minutes, then transfer to a rack. They’re fragile when hot but become delightfully crisp as they cool.

Serve or store. Enjoy plain, or dust lightly with more powdered sweetener once fully cooled.