Ingredients
1 stick (1/2 cup) unsalted butter 
3 medium ripe peaches, halved, pitted and sliced 1/4-inch-thick 
1 cup plus 2 tablespoons granulated sugar 
1 cup unbleached all-purpose flour 
2 teaspoons baking powder 
Pinch fine sea salt 
1 cup whole milk 
1 teaspoon pure vanilla extract 
2 tablespoons fine sanding sugar 
Whipped cream, creme fraiche, or ice cream, for serving (optional) 
Preparation
Preheat oven to 350 degrees.
Melt butter in a 10-inch cast-iron skillet, preferably enameled, over medium heat.
Meanwhile, place peaches in a large bowl and sprinkle with 2 tablespoons granulated sugar.
In another large bowl, whisk together flour, baking powder, and salt. Add remaining 1 cup granulated sugar, milk, and vanilla; whisk until well combined. Whisk in melted butter. Pour mixture into skillet and top with peaches. Sprinkle with sanding sugar.
Bake until top is golden brown and a tester inserted in center comes out clean, 50 to 55 minutes. Serve warm or at room temperature with whipped cream, creme fraiche, or ice cream, if desired.