Choose a large (12 oz or bigger), microwave-safe mug to prevent overflow. Lightly grease the inside with nonstick spray or butter if desired, which helps with cleanup later.

Add the milk, melted butter, and vanilla extract to the mug. Use a fork or small whisk to mix until fully combined and smooth.

Stir in the Kodiak Cake Mix and brown sugar. Mix until just combined—don’t overmix. The batter will be slightly thick.

Fold in a few chocolate chips if using, or sprinkle some on top for extra chocolatey goodness.

Place the mug in the center of the microwave and cook on high for 1 minute. Check the center with a toothpick—if it comes out clean or with a few moist crumbs, it’s done. If still wet, continue cooking in 15- to 30-second intervals, checking after each round.

Let the mug muffin sit for 1–2 minutes before eating. It will be hot! Enjoy straight from the mug or transfer to a plate if you're feeling fancy.