1. Preheat oven to 350°F. Put a baking sheet in the oven.
2. Coat 3 mini loaf pans (5 3/4″ x 3 3/4″) with nonstick spray. In a large bowl, whisk together flour, baking powder, baking soda, salt, and cinnamon. Make a well in the center of the mixture. In a medium bowl, combine the buttermilk, egg, coconut (or vegetable oil), brown sugar, and vanilla. Add wet ingredients to flour mixture and stir just until combined. Gently fold in diced peaches.

For the streusel topping:

1. In a small bowl, whisk together oats, brown sugar, and cinnamon. Use a fork or pastry cutter to cut butter into flour mixture until it forms coarse crumbs. Divide batter evenly between loaf pans. Arrange peach slices over each loaf. Sprinkle with streusel topping.
2. Place pans on preheated baking sheet and bake, rotating pans halfway through, for 25-26 minutes or until a toothpick inserted in the center comes out clean. Remove from oven and cool in pans on a wire rack for 10 minutes, then remove from pans and cool completely. Wrap bread well and store in the refrigerator for up to 2 days. Warm before serving.