Preheat oven to 400 degrees. Bake 6 thin slices
of prosciutto on a rack-lined rimmed
baking sheet until crisp, 6 to 7 minutes.
Let cool; break each into 2 or 3 pieces.
Remove rind of 1 baby watermelon (about
4 pounds). Slice half the watermelon
1/4 inch thick; reserve remaining melon
for another use. Transfer to a large
platter. Refrigerate until ready to use.
Slice 2 scallions (green parts only) on
a very sharp bias. Sprinkle watermelon
with salt and pepper. Drizzle with
2 tablespoons olive oil; top with prosciutto