Step 1

Preheat your oven to 350 degrees F.  Grease two 6-welled donut pans (if you only have one, you'll just have to reuse it once the first batch is baked).  Set aside.

Step 2

In a large microwave-safe bowl, melt the butter.  Whisk in the buttermilk, sugar, egg, and vanilla until well-combined.  In a separate bowl, whisk together dry ingredients - flour, cinnamon, salt, baking soda, and baking powder.

Step 3

Pour the dry ingredients into the wet, and stir to combine with a large spoon or spatula. Stir until the ingredients are just combined, with no big patches of flour. Do not over mix - if you do, the donuts will be tough, and no one wants that.

Step 4

Spoon the batter into the donut cavities, or pipe them in by filling a gallon-sized bag with the batter, then snipping off a corner for a makeshift pastry bag. Fill each cavity about 2/3 of the way full, or else your donuts won't have holes in the middle! The recipe yields 7 or 8 donuts depending on how full you make them (I got 7 once and 8 another time), so if you only have one donut pan, you'll have to bake the first 6 and then the other 1 or 2 afterwards.

Step 5

In a small bowl, whisk together sugars, cinnamon, and flour.  Cut the cold butter into the flour mixture with a fork, pastry cutter, or my favorite method, your fingertips.  Stop when some bits of butter are pea-sized, and some of the mixture looks like coarse sand.

Step 6

Arrange the diced peaches evenly over the batter in each donut cavity, making sure to press them lightly to adhere.

Step 7

Distribute the crumb topping evenly over the peach donut batter, pressing to adhere.  Make sure you press it down so it doesn't fall off during baking.

Step 8

Bake donuts for 10-11 minutes, until lightly browned on the edges and tops (mine were done at 10). Set aside to cool for 2-3 minutes, then remove to a wire rack set over parchment paper or a baking sheet. Bake the remaining one to two donuts now if you only have one pan.

Step 9

Dust the tops of each donut with a light coating of powdered sugar.  Serve warm or at room temperature.