A tender, tangy sourdough quick bread studded with juicy summer peaches, balanced by caramel notes of brown sugar and finished with a delicate vanilla glaze for a fragrant, lightly sweet finish.
Preheat the oven to 350°F (175°C) and prepare a loaf pan (grease or line with parchment).
In a large bowl, whisk together the flour, baking powder, baking soda, and salt.
In a separate bowl, mix the melted butter, sugar, and brown sugar. Whisk in the eggs, sourdough discard, milk, and vanilla.
Add the wet ingredients to the dry ingredients and mix until just combined. Do not overmix.
Fold in the peaches.
Pour the batter into the prepared loaf pan and smooth the top.
Bake for 65–70 minutes, until golden brown and an internal temperature reads 200–205°F (93–96°C), or a tester comes out clean.
Remove from the pan and cool on a wire rack.
For the glaze, stir together powdered sugar, milk or water, and vanilla until smooth. Drizzle over the cooled loaf (optional).