Choose the right mug: Use a microwave-safe mug that holds at least 12 ounces.
A wider mug cooks more evenly than a tall, narrow one.
Melt the butter: Add 1 tablespoon butter to the mug. Microwave for 15–25 seconds until just melted. Swirl to coat the sides to help prevent sticking.
Whisk in the wet ingredients: Crack in 1 large egg, add 2 tablespoons unsweetened almond milk, and 1/2 teaspoon vanilla extract.
Whisk with a fork until smooth.
Add the dry mix: Add 3 tablespoons almond flour, 1 1/2 tablespoons unsweetened cocoa powder, 1 1/2 to 2 tablespoons sweetener, 1/4 teaspoon baking powder, and a pinch of salt. Stir until no dry pockets remain. The batter should be thick but spoonable.
Fold in the extras: If using, stir in 1 tablespoon sugar-free chocolate chips for melty pockets.
Microwave carefully: Cook on high for 45–60 seconds.
Check at 45 seconds. The top should look set around the edges and slightly glossy in the center. If needed, add 10-second bursts until done.
Rest and serve: Let it stand 1–2 minutes.
This finish-cooks the center and improves texture. Top with a small dollop of whipped cream or a few berries if you like.