Choose the right mug: Use a microwave-safe mug that holds at least 10 to 12 ounces.
A wider mug helps the cake cook more evenly.
Mix the dry ingredients: Add almond flour, sweetener, baking powder, and salt to the mug. Stir well with a fork to break up any lumps.
Whisk the wet ingredients: In the same mug, add the egg, melted butter, almond milk, vanilla, and almond extract. Stir until the batter looks smooth and evenly combined.
Scrape the sides: Use the back of the spoon to scrape batter from the sides of the mug so nothing burns during cooking.
Microwave: Cook on high for 60 to 90 seconds.
Start with 60 seconds, then check. The top should look set and spring back lightly when touched.
Adjust if needed: If the center is still wet, microwave in 10-second bursts. Avoid overcooking; it can make the cake dry.
Rest: Let the mug cake stand for 1 minute.
This helps the crumb set and keeps it tender.
Top and serve: Add whipped cream, sliced almonds, or cinnamon if you like. Enjoy warm straight from the mug or tip it onto a plate.