Set a fan forced oven to 180 °C (360 °F) and let it come fully to temperature. A properly heated oven gives the edges a head start so they set before the centers overbake.

Melt the butter in a saucepan over medium heat until it is fully liquid and hot. It should look glossy and pourable, with no solid streaks left in the pan.

Pour the hot butter into a mixing bowl with the erythritol and beat until the two come together. The mixture will look grainy and pale, which is normal at this stage.

Add the vanilla and egg, then beat on low for about 15 seconds. Stop as soon as the mixture turns smooth and slightly glossy so the egg does not aerate.

Tip in the almond flour, baking powder, xanthan gum, and salt, then beat until fully combined. The dough should pull away from the sides of the bowl and feel soft and malleable rather than sticky.

Press the dough into a mass, lift it out of the bowl, and work in the chocolate chips with your hands or a silicone spatula. Kneading by hand keeps the chips intact instead of smearing them through the dough.

Divide the dough into 12 portions with a small ice cream scoop and space them on a lined baking tray. Even scoops mean even baking, and a lined tray keeps the buttery bottoms from catching.

Bake for 10 to 12 minutes at 180 °C (360 °F), checking the tray at the 6 to 7 minute mark. If the mounds are still sitting tall and round, press each one down gently with the back of a fork.

Pull the tray while the centers still look slightly undercooked and the edges are lightly golden. A rich, nutty, buttery aroma tells you they are done even when the middles look pale.

Let the cookies rest on the tray for 15 minutes before serving. They firm up as they cool, moving from fragile and soft to sturdy with a tender bite.