Grease a 12-ounce (or larger) mug with nonstick cooking spray or butter. I prefer to use a wider mug that’s about 16 ounces for this recipe. Set aside.
In a small mixing bowl, whisk together the melted butter, milk, sugar, egg yolk, vanilla extract, and almond extract until well combined.
2 tablespoons unsalted butter, 3 tablespoons whole milk, 3 tablespoons granulated sugar, 1 large egg yolk, ½ teaspoon pure vanilla extract, ⅛ teaspoon almond extract
Add the flour, baking powder, and salt and whisk until just combined, then stir in the sprinkles.
⅓ cup all-purpose flour, ½ teaspoon baking powder, Tiny pinch of salt, 1 tablespoon sprinkles
Pour the batter into the prepared mug and add a few extra sprinkles on top. Microwave for 60-90 seconds or until the top of the cake is set (no longer wet) and a toothpick or skewer inserted into the center comes out clean. My microwave is 1200W and mine usually takes 75 seconds to fully cook through.
Carefully remove it from the microwave (the mug will be hot!) and allow it to cool slightly, then top with your favorite toppings, and enjoy!