01 - In a microwave-safe mug (at least 12 oz capacity), whisk together cottage cheese, egg, milk, melted butter, lemon juice, and vanilla extract until smooth and fully combined.
02 - Add flour, sugar, lemon zest, baking powder, and salt to the mug. Mix until just combined, ensuring you scrape down the sides of the mug to incorporate any dry pockets.
03 - Microwave on high power for 1 minute 30 seconds to 2 minutes, or until the cake has risen and the center is completely set.
04 - Allow the cake to cool for 2-3 minutes before enjoying directly from the mug. Optionally garnish with powdered sugar, extra lemon zest, or a spoonful of yogurt.