Prep the pan and oven: Preheat your oven to 350°F (175°C). Grease a 9x5-inch loaf pan and line it with a parchment sling for easy removal.

Prep the peaches: Peel, pit, and dice the peaches into small chunks (about 1/2-inch). Toss with lemon juice and 1 tablespoon flour. Set aside.

Mix dry ingredients: In a medium bowl, whisk flour, baking powder, baking soda, salt, and cinnamon.

Mix wet ingredients: In a large bowl, whisk granulated sugar, brown sugar, and oil until combined. Whisk in eggs one at a time. Stir in yogurt and vanilla until smooth.

Combine: Add the dry ingredients to the wet and stir gently until mostly combined. Fold in the diced peaches, taking care not to overmix.

Fill the pan: Pour the batter into the prepared loaf pan and smooth the top. If using, mix the cinnamon and sugar, then sprinkle evenly over the batter.

Bake: Bake for 55–70 minutes, or until a toothpick inserted in the center comes out clean or with a few moist crumbs. If the top is browning too fast, tent loosely with foil during the last 15 minutes.

Cool: Let the loaf cool in the pan for 15 minutes. Lift it out using the parchment and cool completely on a wire rack before slicing.