Preheat oven to 350 degrees F (175 degrees C). Lightly grease a 9x12-inch baking dish.
Mix 3 cups flour, 2 teaspoons baking powder, and 1 teaspoon salt together in a bowl. Stir in 1 cup white sugar, brown sugar, 1 cup melted butter, 2 eggs, and vanilla extract until batter is just combined.
Pour batter into the prepared baking dish.
Bake in the preheated oven until slightly done, 5 minutes.
Beat 1 cup white sugar and 1 cup melted butter together in a bowl until creamy. Stir in pumpkin puree, 1 cup flour, 2 eggs, 1 tablespoon cinnamon, pumpkin pie spice, nutmeg, 1 teaspoon baking powder, and 1 teaspoon salt until batter is smooth.
Pour batter over the partially-baked bottom layer.
Mix 1 tablespoon white sugar and 1 teaspoon cinnamon together in a small bowl; sprinkle over pumpkin layer.
Bake in the preheated oven until a knife inserted in the center of the cake comes out clean, about 35 minutes.