Heat the oven to 350℉. Prepare a large loaf pan (9"x5") and spray it with cooking spray, or line with parchment paper for easy removal for slicing. Set aside.
In a large mixing bowl, whisk together the all-purpose flour, quick oats, granulated sugar, light brown sugar, mini chocolate chips, baking powder, baking soda, cinnamon, and salt until everything is well combined.
1⅓ cup all-purpose flour, 2/3 cup quick oats, 1/3 cup granulated sugar, 1/3 cup light brown sugar, 1/3 cup mini chocolate chips, 1½ teaspoons baking powder, 1 teaspoon baking soda, ½ teaspoon ground cinnamon, ½ teaspoon salt
In a separate smaller bowl, whisk the buttermilk, egg, and melted butter until combined.
1 cup buttermilk, 1 large egg, 3 tablespoons butter
Add the wet ingredients into the larger bowl of dry ingredients, and stir gently with a rubber spatula just until combined and no flour streaks remain in the batter.
Evenly spread the batter into the prepared loaf pan and smooth out the top. Sprinkle a few additional mini chocolate chips and quick oats on top (optional, if wanted).
Bake for 40-50 minutes or until a toothpick inserted into the center comes out clean.
Remove the bread from the oven and allow it to cool inside the loaf pan before slicing. This bread is delicious eaten warm or at room temperature.