In a large bowl, beat the butter, brown sugar, and granulated sugar on medium speed until light and fluffy, about 2 minutes, scraping the bowl once.

Beat in the egg and vanilla extract on low speed just until smooth and no yellow streaks remain, about 30 seconds.

Sprinkle the flour, baking soda, and salt over the wet mixture. Fold with a spatula until a few flour streaks remain, then add the granola and chocolate chips. Fold gently until no dry pockets hide at the bottom.

Preheat oven to 350°F (175°C) and line two baking sheets with parchment. Scoop 2-tablespoon mounds of dough onto the sheets, spacing them 2 inches apart. Flatten each slightly. Bake one sheet at a time on the middle rack for 12 to 14 minutes, until edges are golden and tops look set. Slide the parchment onto a wire rack, cool 5 minutes, then transfer cookies to the rack to cool completely.