Adapted from: Annie's Eats
We had a whole bunch of peaches from the CSA that needed to be used this weekend, and this was the recipe I chose. It can easily be doubled by using a 9x14 pan and increasing the cooking time for the peaches by 5 min and the cook time for the whole thing with the biscuits by an additional 5 minutes.
For the filling:
3 lbs. ripe but firm peaches
1/4 cup sugar
1 tsp. cornstarch
For the biscuit topping:
2/3 cup all-purpose flour
1/3 cup whole wheat flour
3 tbsp. plus 1 tsp. sugar, divided
3/4 tsp. baking powder
1/4 tsp. baking soda
1/4 tsp. salt
5 tbsp. cold unsalted butter, cut into 1/4-inch cubes
1/2 cup plus 1 Tbsp plain whole milk yogurt (2% Greek yogurt worked fine)
Adjust an oven rack to the lower-middle position. Preheat the oven to 425° F. For the filling, peel the peaches and then cut each into 8 wedges, removing the pits as you go. Gently toss the peaches and sugar together in a large bowl and let stand for 30 minutes, tossing several times. Drain the peaches in a colander set over a bowl. Whisk together 1/4 cup of the drained juice with the cornstarch in a small bowl. Toss the peaches with the juice mixture and transfer to a 8-inch square glass baking dish (I used a round pie plate). Bake until peaches begin to bubble around the edges, about 10 minutes.
Meanwhile, prepare the biscuit topping. In the food processor, combine the flours, 3 tablespoons sugar, baking powder, baking soda and salt. Pulse to combine. Scatter the butter over the flour mixture and pulse until the mixture resembles coarse meal, about ten 1-second pulses. Transfer to a medium bowl; add the yogurt and toss with a spatula until a cohesive dough is formed. (Be careful not to overmix.) Break the dough into 6 evenly sized but roughly shaped mounds and set aside.
After the peaches have baked 10 minutes, remove the peaches from the oven and place the dough mounds on top, spacing them at least 1/2-inch apart (they should not touch). Sprinkle each mound with the remaining sugar. Bake until the topping is golden brown and fruit is bubbling, 16-18 minutes. Cool on a wire rack until warm, about 20 minutes; serve.