Chocolate chip cookie in a mug

(From http://www.number-2-pencil.com/2012/03/06/chocolate-chip-cookie-in-cup/)

• 1 TBS butter
• 1 TBS sugar
• 1 TBS brown sugar
• dash of vanilla extract
• pinch of salt
• 1 egg yolk
• scant 1/4 c. flour
• 2 heaping TBS chocolate chips

Melt butter in a mug in the microwave.  Add sugars, vanilla, and salt and stir.  Stir in yolk.  Stir in flour.  Stir in chocolate chips.  Microwave until done (probably 40-60 seconds).