Preheat your oven to 350°F (175°C). Line your baking pan with parchment paper and lightly grease it. This ensures the cake releases easily and keeps the edges perfectly soft.

In a large bowl, whisk together flour, brown sugar, granulated sugar, baking powder, baking soda, salt, and cinnamon. The mixture should look light and evenly combined, with no lumps of sugar remaining.

In another bowl, whisk the eggs until smooth. Add buttermilk, melted butter, and vanilla extract. The mixture will be creamy and slightly golden, with a warm, sweet aroma.

Pour the wet ingredients into the dry mixture. Gently fold everything together using a spatula until just combined. The batter should be thick but smooth—avoid overmixing to keep the cake tender.

Fold in the sliced peaches, making sure they are evenly distributed throughout the batter. Each piece will bake into soft, juicy pockets of flavor.

Pour the batter into your prepared pan and spread it evenly. If using the optional topping, sprinkle brown sugar over the surface and drizzle with melted butter.

Bake for 35–40 minutes, or until the top is golden brown and a toothpick inserted in the center comes out clean. The aroma of caramelized sugar and baked peaches will fill your kitchen.

Allow the cake to cool in the pan for 10–15 minutes before transferring to a cooling rack. Serve warm or at room temperature for the best texture and flavor.