1/2 cup (1 stick) unsalted butter softened, plus more for skillet
3/4 cup plus 2 tablespoons sugar
3 large eggs
1 teaspoon vanilla extract
1 1/4 cups all-purpose flour (spooned and leveled)
1/4 teaspoon baking powder
1/2 teaspoon salt
1 1/2 lbs. peaches pitted, peeled, and cut into 1/2-inch pieces (4 cups)
1/2 teaspoon ground cinnamon
1/3 cup sliced almonds
Preheat oven to 350 degrees. Butter a 10-inch cast-iron skillet, nine-inch square baking pan, or a two-quart shallow baking dish. In a large bowl, cream butter and 3/4 cup sugar with an electric mixer until fluffy. Add eggs, one at a time, and vanilla; beat to combine.
In a medium bowl, whisk together flour, baking powder, and salt. With mixer on low speed, gradually add flour mixture to butter mixture; beat until incorporated. Fold in peaches.
Spread batter in prepared skillet. In a small bowl, mix together remaining 2 tablespoons sugar, cinnamon, and almonds. Sprinkle mixture over top; bake until a toothpick inserted in center comes out clean and topping is golden, 45 to 50 minutes. Let cool 20 minutes before serving.