Set the oven rack to the vertical middle and preheat the oven to 400 degrees. Line your muffin tins with paper cups or spray with non-stick spray.

Set aside 2 tablespoons of the ground oats. In medium mixing bowl combine the remaining oats with the flour, baking powder, baking soda, cinnamon, nutmeg and salt. Toss the diced apples with 2 tablespoons of the flour mixture then set both aside.

In a large mixing bowl or stand mixer bowl, beat together the oil and sugar until combined. Add the eggs one at a time stirring on low speed until the batter is a uniform color.

Add ⅓ of the total buttermilk and stir a few times. Then add ½ of the flour mixture and mix until it has just barely incorporated into the batter. Continue to alternate adding the remaining buttermilk and flour mixture mixing just enough to combine between each step. Finish with the buttermilk and stir a few extra times so the batter is a uniform color and consistency.

Fold the apples into the batter so they are evenly distributed.

Scoop the batter into the muffin cups by the ¼ cup - adjust the amount if needed so the batter fills most of the cup but does not come to the top. Sprinkle the muffins with the reserved oats then bake for 18-22 minutes. The muffins should be golden on top and slightly springy to the touch (be careful they are hot).

Let the muffins cool to just above room temperature before serving.