Preheat oven to 425 degrees.

Defrost peaches completely in a colander.

Gently toss peaches and sugar together in a large bowl and let stand for 30 minutes, tossing several times.

Drain peaches in a colander set over a large bowl, reserving 2 tablespoons of the drained juice and discarding the rest.

Whisk the reserved peach juice, cornstarch, lemon juice, and salt together in a small bowl.

Toss the peach juice mixture with the peach slices.

Transfer the peach mixture to an 8-inch-square glass baking dish.

Bake until peaches begin to bubble around the edges, about 15 to 20 minutes.

While peaches are baking, in a food processor, pulse flour, 3 tablespoons sugar, baking powder, baking soda, and salt to combine.

Scatter cold butter cubes over the flour mixture and pulse until the mixture resembles coarse meal, about ten 1-second pulses.

Transfer the mixture to a medium bowl.

Add yogurt and toss with a rubber spatula until a cohesive dough is formed. (Don't overmix the dough.)

Break the dough into 6 evenly sized but roughly shaped mounds.

Set aside the dough mounds.

When peaches bubble around the edges, remove the baking dish from the oven.

Place dough mounds on top of the peach mixture, spacing them at least 1/2 inch apart.

Sprinkle each mound with a portion of the remaining 1 teaspoon sugar.

Bake until the topping is golden brown, about 18 minutes.

Cool the cobbler on a wire rack until warm, about 20 minutes, before serving.