Preheat oven to 375 and grease a medium (1.5-2 qt) glass baking dish with butter.

If you haven't sliced your peaches into chunks, do that now (rough chop, doesn't matter if they're all the same size).

Place peach chunks, brown sugar, and 4 tsp of flour (or 2 tsp of cornstarch) into the baking dish and stir to evenly coat until all sugar and flour are incorporated.

Bake in the preheated oven for 10 minutes before placing the biscuit topping on.

While peaches are baking, make your biscuit topping dough.

Place flour, baking powder, baking soda, salt, brown sugar, and cinnamon into a medium-sized mixing bowl. Stir to combine.

Now grate cold butter over the flour mixture using the large holes of a box grater. Stir butter pieces into the flour mixture until distributed evenly. (You can also use a fork to cut the butter into the flour mixture until pea-sized pieces form.)

Finally, add in the buttermilk (or milk) and sourdough starter, Stir until a wet dough forms. This will be wet, you want that. Don't add extra flour. Set aside until peaches are done baking.

Take peaches out of the oven (but leave it turned on) and stir to evenly distribute the juices.

Use your fingers to drop pinches of dough all over the top of the peaches until all the dough is used up.

Bake for 35-40 minutes or until bubbling and golden brown.

Enjoy with some whipped cream or ice cream!