1 tablespoon butter, softened or non-stick baking spray
1 1/2 cups all-purpose flour
1 1/4 cups old-fashioned oats
1 tablespoon baking powder
1/2 teaspoon kosher salt
1/4 cup granulated sugar
½ cup cold butter, cut into 8 tablespoons (1 stick)
1 large egg
½ cup buttermilk
1 teaspoon apple cider vinegar
1 teaspoon pure vanilla extract
1 cup fresh or frozen blueberries
2 tablespoons raw sugar (optional)
Preheat the oven to 425˚F. Use a paper towel to spread butter over the inside of each cup in the muffin pan.
In a standing mixer or large bowl with electric beaters, blend the flour, oats, baking powder, salt and sugar on low speed until well mixed, about 30 seconds.
Add cubed cold butter and mix again until you see uniform chunks of batter, about 2 minutes.
Crack the egg into the mixing bowl. Add buttermilk, vinegar, and vanilla. Beat again until just mixed, about 30 seconds.
Add the blueberries. Use the spatula to gently fold the blueberries into the dough
Use an ice cream scoop to measure batter and place in muffin pan cups. Use clean hands to flatten batter in muffin pan cups. Sprinkle with raw sugar, if using. Bake for 10-12 minutes until just golden on the outside.