Combine oats and buttermilk in a medium bowl; cover and refrigerate overnight.
Preheat oven to 350.
Lightly spoon flour into dry measuring cups; level with a knife. Place buttermilk mixture, flour and next 6 ingredients (flour through eggs) in a large bowl; beat with a mixer at medium speed until smooth. Fold in blueberries.
Spoon 1/4 cup batter into each of 24 muffin cups coated with cooking spray. Bake for 15 minutes or until muffins spring back when touched lightly in center. Remove muffins from pans immediately; place on a wire rack.
Bake
2007, 2008, 2009, 2014