Preheat oven to 375°F (190°C). Lightly grease an 8x8 or 9x9 inch baking dish.

Prepare the filling: In a large bowl, combine the drained peaches, reserved 1/2 cup peach syrup, 1/4 cup sugar, vanilla extract, cinnamon, nutmeg, and cornstarch. Stir gently to combine. Pour the mixture into the prepared baking dish.

Prepare the topping: In a separate medium bowl, whisk together the flour, 1/4 cup sugar, baking powder, and salt.

This is the key for a fluffy topping: Add the very cold, cubed butter to the dry ingredients. Using your fingertips or a pastry blender, quickly cut the butter into the flour mixture until it resembles coarse crumbs with some pea-sized pieces of butter remaining. It is crucial not to overmix; warm hands or too much mixing will melt the butter, leading to a tough topping.

Pour in the milk. Stir just until moistened with a fork. The dough will be shaggy and sticky. Again, do not overmix to ensure tenderness.

Drop spoonfuls of the dough evenly over the peach mixture. Leave some small gaps for the peaches to bubble up.

For the golden finish: Sprinkle the reserved 1 teaspoon of granulated sugar evenly over the top of the biscuit dough before baking. This helps create that beautiful caramelization and a gorgeous golden crust.

Bake for 35 to 45 minutes, or until the peach filling is bubbly and the topping is beautifully golden brown and cooked through. If the topping begins to brown too quickly, you can loosely tent it with foil for the last 10 to 15 minutes of baking.

Let cool slightly before serving warm.