- Preheat oven to 425 degrees
- Grease a large baking sheet with cooking spray. Working with one sheet of the puff pastry, keep remaining sheet wrapped and cold, roll out onto a lightly floured surface to a 14-inch square
- Brush a thin layer of mustard, cover with half of the prosciutto slices, slightly overlapping and leaving a ½ inch border around the edges.
- Sprinkle with one cup of cheese. Roll the pastry tightly, from the long side. Pinch seams to seal and tuck the ends under. Repeat with the remaining sheet.
- Cut into ¼ inch pieces and place, cut side up, 1 inch apart onto the baking sheet. Bake for 10-15 minutes of until golden brown.
Note: these can be made in the morning, just wrap in foil and refrigerate. Approximately 1-2 hours before the party, slice them and place them on the greased baking sheets on top of the stove. Cover with the wrap or the foil.