Preheat and prep: Heat the oven to 350°F (175°C). Line two baking sheets with parchment paper or silicone mats.
Mix the dry ingredients: In a medium bowl, whisk the powdered sweetener, cocoa powder, baking powder, and salt until no lumps remain.
Whisk the wet ingredients: In a small bowl or measuring cup, whisk the egg whites, vanilla, and melted butter until smooth.
Combine: Pour the wet mixture into the dry ingredients.
Stir with a spatula until a thick, glossy batter forms.
Adjust consistency: If the batter looks dry or crumbly, add almond milk 1 teaspoon at a time. You want a thick, scoopable batter—not runny.
Add chips: Fold in the sugar-free chocolate chips, if using.
Portion: Scoop heaping tablespoons of batter onto the prepared sheets, spacing them 2 inches apart. The cookies spread a little.
Smooth the tops: For a prettier finish, lightly dampen your fingertips and smooth any rough edges.
Bake: Bake for 9–11 minutes, until the tops are glossy and cracked and the edges look set.
The centers should still be soft.
Cool: Let the cookies cool on the baking sheet for 10 minutes before transferring to a rack. They firm up as they cool.