Ingredients
Equipment
Method
- Place the butter in your microwave-safe mug and microwave for about 15 to 20 seconds until completely melted.
- Add both the granulated sugar and brown sugar to the melted butter in the mug. Stir vigorously with a spoon until the mixture looks smooth and slightly glossy, which takes about 20 seconds of stirring.
- Add the vanilla extract and pinch of salt to the butter-sugar mixture and stir to combine.
- Drop in just the egg yolk and stir until the mixture becomes smooth and uniform in color.
- Add the flour all at once and stir gently until no dry streaks remain, being careful not to overmix. Stop stirring as soon as you no longer see flour.
- Fold in the chocolate chips, reserving a few to press into the top for presentation if desired.
- Use your spoon to press the dough down gently and smooth the top slightly so it cooks evenly.
- Microwave on high power for 40 to 60 seconds, watching carefully through the window. The cookie is done when the edges look set but the center still appears slightly underdone.
- Let the mug cookie cool for at least 2 minutes before eating. The brief cooling time lets the texture set properly.
Notes
Every microwave cooks differently, so start checking at 40 seconds and add time in 5-second increments if needed. The center should look barely set and still a bit glossy when you stop cooking. Use a mug that holds at least 12 ounces to prevent overflow. Best enjoyed fresh but can be stored covered in the refrigerator for up to 2 days and reheated for 10-15 seconds.