
Preheat the oven to 400°F. Line a standard muffin tin with paper liners.
In a large bowl, whisk together the flour, sugars, salt, and baking powder. Set aside.
In a small bowl, whisk together the buttermilk, butter, egg, and vanilla. Pour into the dry ingredients and stir with a rubber spatula until just combined. Gently stir in the chocolate chips. Do not overmix.
Using a large cookie scoop or a spoon, divide the muffin batter evenly among the muffin tin cups.
Bake until golden brown and a toothpick inserted in the center comes out clean, about 20 to 22 minutes. Let cool until barely warm.
Serve or store in an airtight at room temperature for 3 days. Reheat in the microwave for about 15 seconds if desired. Muffins can also be frozen in an airtight container for up to 3 months.