Prepare your mug. Melt some butter right in your mug to kick things off.
Make your batter. Stir in light brown sugar, milk, and vanilla extract until it’s all smooth. Then, mix in flour, cinnamon, baking powder, and a pinch of salt just until you’ve got a nice batter.
Make a quick streusel. Melt more butter, then stir in flour, sugar, cinnamon, and salt until it’s crumbly. Sprinkle that right on top of your batter.
Microwave until the cake is fluffy and mostly set (start checking around 2 minutes).
Make the glaze. If you’re feeling extra, whip up a quick glaze with powdered sugar and a splash of milk, then drizzle it over the top. Grab a spoon and enjoy it warm, trust me it’s best fresh out the mug.
