Preheat oven to 350 degrees F. Original recipe said 375, but my first batch browned too quickly at 375. Either heat works, but I think 350 is safer.

Mix together flour, baking soda, and salt in a small bowl. Beat together butter, sugars, and vanilla in a medium bowl with an electric mixer at high speed until pale and fluffy, about 3 minutes, then beat in egg until combined well. Reduce speed to low or by hand stir in the flour mixture and mix until just combined. Stir in granola and chocolate chips.

Drop 18 mounds (about 2 level tablespoons per mound) of batter about 2 inches apart onto 2 ungreased large baking sheets, then pat each mound into a 2 ½-inch round.

Bake cookies, switching position of sheets halfway through baking, until pale golden, about 10-13 minutes. Cool on sheets 1 minute, then transfer to racks to cool completely.