In a small bowl mix Calabrian chilli paste, vinegar and maple. Gently toss the peach slices in this mixture.
Place the toasted baguette halves on a plate, cut side up. Drizzle a little of the chilli-vinegar mixture on the bottom half of the bread.
Layer cheddar slices, the peach mixture, prosciutto, and basil leaves. Drizzle more of the dressing over the top.
Close the sandwich with the top half of bread, press lightly, and cut in half to serve.