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vanilla mug cake interior crumb shown on spoon with rainbow sprinkle streaks, funfetti texture
Luna Hossain

Vanilla Mug Cake Recipe

A tender, funfetti-style vanilla mug cake made in one mug with no mixer and no oven — soft, open crumb loaded with rainbow jimmies and ready in under 5 minutes.
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Prep Time 3 minutes
Cook Time 2 minutes
Total Time 5 minutes
Servings: 1 mug cake
Course: Easy Cakes
Cuisine: American
Calories: 290
Ingredients Equipment Method Notes

Ingredients
  

  • For the Mug Cake:
  • - 4 tablespoons 30g all-purpose flour, spooned and leveled
  • - 2 tablespoons 25g plain white granulated cane sugar
  • - ½ teaspoon 2g baking powder, checked for freshness
  • ⅛ teaspoon (0.5g) fine sea salt
  • - 3 tablespoons 46ml whole milk, room temperature
  • - 1 tablespoon 14g unsalted butter, melted and cooled slightly
  • - ¼ teaspoon pure vanilla extract
  • - 1 tablespoon 15g rainbow jimmies (rod-shaped sprinkles — not nonpareils)
  • For the Topping:
  • - 3 tablespoons whipped cream canned, or freshly whipped full-fat heavy whipping cream (minimum 36% fat), whipped to firm peaks and stabilized with ½ teaspoon powdered sugar — or canned whipped cream
  • - 1 teaspoon rainbow jimmies for scattering on top

Equipment

  • Required:
  • 12 oz (350ml) or larger microwave-safe ceramic mug — straight-walled, C-handle style preferred
  • Kitchen scale (strongly recommended — gram weights are more reliable than volume for this recipe)
  • Small microwave-safe bowl or ramekin (for melting butter separately)
  • Fork (for mixing the batter in the mug)
  • Measuring spoons — tablespoon and teaspoon
  • Microwave
  • Optional:
  • Oven thermometer (not applicable here, but if your microwave has known hot spots, rotate the mug halfway through cooking)
  • Piping bag fitted with a star tip (for a formally piped whipped cream swirl — a spoon works fine for a rustic dollop)
  • Kitchen timer (set it for 70 seconds and check — do not estimate microwave time by feel)

Method
 

  1. Add the flour, sugar, baking powder, and fine sea salt to a 12 oz (350ml) or larger microwave-safe ceramic mug and stir with a fork for 10 to 12 strokes until evenly combined with no baking powder pockets visible.
  2. Add the whole milk, melted and slightly cooled butter, and vanilla extract directly into the mug and mix with slow bottom-scraping strokes for approximately 20 strokes until the batter is smooth, thick, and uniform with no dry flour remaining at the base.
  3. Add the rainbow jimmies and fold in with 5 to 6 gentle strokes — work quickly and move immediately to the microwave, as jimmies begin releasing dye on contact with wet batter.
  4. Microwave on high power for 70 seconds (1100-watt microwave) — adjust to 80 to 85 seconds for 700 to 800 watt microwaves, or 75 seconds for 900 to 1000 watt microwaves — and stop when the surface is matte, the edges have slightly retracted from the mug wall, and the cake has reached its maximum height.
  5. Rest the mug on the counter for 60 to 90 seconds — do not skip this step, as carryover heat from the hot ceramic mug finishes the center during this time.
  6. Top with whipped cream and scatter the remaining rainbow jimmies over the cream immediately before serving — eat directly from the mug while still warm.

Notes

- Mug size: use 12 oz (350ml) minimum — smaller mugs will overflow during cooking.
- Baking powder: freshness-test before using — drop a pinch in hot water, it must bubble actively.
- Flour: spoon and level, do not scoop — or weigh at exactly 30g for accuracy.
- Salt: do not skip — ⅛ tsp suppresses baking powder bitterness and amplifies vanilla. Missing = flat-tasting cake.
- Butter: melt and cool slightly before adding — hot butter creates a greasy, uneven batter.
- Sprinkles: use rainbow jimmies, not nonpareils — nonpareils bleed dye and discolor the batter.
- Microwave wattage: adjust cook time based on your microwave — check wattage inside the door.
- Do not overcook: rubbery texture is caused by 15 to 20 extra seconds — pull at matte surface.
- Storage: eat immediately — mug cake degrades within 2 hours and does not refrigerate or freeze well.
- Make ahead: pre-measure dry ingredients into a zip-lock bag, store up to 1 month at room temperature.
- Scaling: cook each mug separately — two mugs simultaneously undercook both.
- Leavening scaling note: baking powder does not scale linearly in microwave cooking — make individual mugs.
- Allergens: contains gluten (all-purpose flour), dairy (butter, whole milk, whipped cream). Egg-free as written.
- Tip: grease the inside of the mug with a thin layer of butter before adding batter for cleaner crumb release.