Mix the dry ingredients: In a microwave-safe mug (10 to 12 oz capacity), whisk together the flour, sugar, baking powder, and salt.
Add the wet ingredients: Stir in the plant-based milk, oil (or melted butter), and vanilla extract. Mix just until combined, don’t overmix. Fold in the white chocolate chips or sprinkles, if using.
Microwave: Cook on high for 1 minute 15 seconds to 1 minute 30 seconds, until the top looks mostly set but still slightly moist. Every microwave is different, so start checking at the 1-minute mark. It’s better to slightly undercook than overcook.
Cool & enjoy: Let the mug cake cool for 1–2 minutes, then top with vegan ice cream or whipped cream, or enjoy as-is.
