In a small ramekin or microwavable cup, combine softened butter and both sugars; stir well with a spoon. Stir in beaten egg and vanilla extract. Stir in flour, baking soda, and salt just until combined. Stir in chocolate chips.
Microwave on high for 35-40 seconds. Let cookie rest at room temperature for about 10 seconds before devouring.
253.2 calories, 13.8 grams fat, 8.4 grams saturated fat, 2.9 grams fiber, 17.5 grams sugars, 2.4 grams protein