Prepare a baking sheet with cooking spray, place one frozen loaf Rhodes bread onto pan. Cover with a towel and let it rise at room temp for 4 hours. Using a pair of scissors, wash them off before if need be. Cut slits into the top of the bread, cutting ¾ of the way into the bread loaf.
Prepare peaches. Once peaches are sliced, spread about a teaspoon mascarpone on each peach slice, then sprinkle with sugar and cinnamon. In between each slit add 3 peach slices. Repeat with remaining peaches. Cover and let the bread sit for 30-45 minutes. Preheat oven to 350 degrees. Bake for 25 minutes. Open oven brush melted butter over bread and sprinkle with sugar and bake another 3-5 minutes. Remove from oven and serve.