Preheat oven to 400°F. Grease a 12-cup muffin tin or line with paper liners. Set aside.
In a large bowl, combine oat flour, all-purpose flour, chopped pecans, baking powder, and baking soda.
In a separate bowl, combine egg, greek yogurt, honey, butter, and vanilla extract; mix well.
Stir the wet mixture into the dry ingredients just until moistened, don’t overmix. Then fold in 1 cup diced peaches.
Fill muffin cups two-thirds full, and sprinkle coconut sugar on tops. Bake at 400°F until muffins test done with a toothpick.
Cool in the pan for 10 minutes before removing to a wire rack.