Add rolled oats and buttermilk to large mixing bowl. Let stand for 1 hour in the refrigerator.
Preheat oven to 400 F. Use convection if available.
Add egg, brown sugar, vanilla, and canola oil to the oat mixture in mixing bowl. Stir until combined.
In another large bowl, whisk together flours, salt, baking powder, and baking soda. Stir into oat mixture until just combined. Fold in chocolate chips.
Spoon batter into muffin cups (cups will be nearly full) and bake for 18-20 minutes until golden.