On a pan over medium heat, cook the peaches, sugar and salt (if using canned peached, go straight to step 3.)
Cook for a few minutes until the sugar dissolves and the peaches release some juices. A caramel will form, its consistency has to be similar to that of canned peaches. Take off the heat and set aside.
For the batter:
Preheat the oven to 350º F (176º C). Cut the butter into small pieces and put them on cake pan of about 9 x 13 inches. Put the pan in the oven while it´s preheating so the butter melts, then take the pan out of the oven.
In a big bowl mix the flour, sugar, baking powder and salt. Stir in the milk just until combined. Add this batter to the pan with melted butter and even all out using a rubber spatula.
Spoon the peaches and caramel on top carefully. Spread some ground cinnamon on top to taste.
Bake at 350º F (176º C) for 35 to 40 minutes. Serve while still hot with a scoop of vanilla ice cream if desired.