Spray a mug with cooking spray. Combine flour, yogurt, and milk, sweetener and blueberries in the mug. Sprinkle with golden sugar.
Microwave on high for one minute.
Check for doneness. If top is wet, Microwave for 30 more seconds. Poke the muffin wiht a finger. If it springs back, it's done. If not, 30 more seconds until done.