Preheat your oven to 375°F (190°C). While the oven is preheating, place the butter in a cast iron skillet and place it in the oven to melt. Keep an eye on it to make sure it doesn't burn. Once it melts, remove the cast iron skillet from the oven and set it aside.
Prepare Homemade Self-Raising Flour by combining 1 ½ cups all-purpose flour, 2 teaspoons of baking powder, and ½ teaspoon of salt. Mix the ingredients well.
Add brown sugar, white sugar, and milk and vanilla to the flour mixture and mix them thoroughly until you have a smooth batter.
Pour the batter over the melted butter in the cast iron skillet. As tempting as it is, do not stir.
Open both cans of peaches and reserve the syrup from both cans. Spoon the peaches evenly over the batter and pour about ¼ cup of the reserved juice over the peaches. Again, do not stir.
Sprinkle 2 tablespoons or more of cinnamon sugar over the top of your dump cake and bake at 375°F for 35-40 minutes, until top is golden brown and center is bubbling. Let cool for 15-20 minutes before serving warm with ice cream.