1-Step 1: Make the Crumb Topping Combine ¾ cup all-purpose flour, 2 tablespoons granulated sugar, 3 tablespoons packed light brown sugar, and heaped ⅛ teaspoon salt (if using) in a medium bowl. Add 5 tablespoons melted unsalted butter and stir until the mixture forms large crumbs. Cover and set aside for later.

2-Step 2: Prepare the Cake Batter Whisk the 6 tablespoons of browned unsalted butter with ½ cup packed light brown sugar, ¼ cup granulated sugar, and 1 teaspoon vanilla extract until pale and fluffy. Whisk in 2 large eggs one at a time until the mixture is light and creamy, then mix in ⅓ cup full fat plain yogurt. Sift 1 ⅓ cups all-purpose flour, 1 ½ teaspoons baking powder, and ¼ teaspoon salt into a small bowl. Fold this into the wet ingredients by hand until mostly combined, leaving some streaks of flour. Gently fold in ⅓ cup plus 1 tablespoon milk until fully mixed, then spread the batter evenly into the prepared pan.

3-Step 3: Add the Peaches In a bowl, toss 3 ½ cups chopped fresh peaches with 2 tablespoons all-purpose flour and 2 tablespoons packed light brown sugar to coat evenly. Scatter the peaches over the cake batter in the pan.

4-Step 4: Top and Bake Sprinkle the crumb topping evenly over the peaches. Bake for 40-50 minutes until the topping is lightly golden and a toothpick inserted in the center comes out clean. Let the cake cool on a wire rack for at least 30 minutes before serving, using the parchment overhang to lift it out.