In a skillet over medium-high heat, lightly brown the butter. Add the garlic and cook until it is light brown. Add the sage and cook until aromatic. Add the corn kernels and cook for 1 minute. Season with salt and pepper. Pour in the cream and simmer until it is reduced by half, about 4 to 5 minutes; let cool. Spoon the corn over the bread and serve with a slice of prosciutto on each.