Preheat oven to 375℉.

Place the asparagus on a baking sheet and drizzle with olive oil, salt and pepper. Toss to evenly coat and roast for about 10 to 15 minutes or until crispy. Remove from oven and allow to cool completely and cut them in half.

Work with one sheet of puff pastry at a time, keeping the other one in the fridge until ready to use. Cut each sheet into 4 long triangles. Spread with a bit of mustard (at the thickets part of the triangle). Sprinkle with a bit of cheese, a prosciutto slice on each, and a few pieces of asparagus (cut in half). Roll the croissants into tight logs, starting at the widest part and rolling down towards the thin pointed edge. Place point side down, on a baking sheet lined with parchment paper. Repeat with the second puff pastry sheet. You should get 8 croissants in total.

Brush them with egg wash and bake for about 25 to 30 minutes or until golden brown and flaky. Allow to cool slightly before serving. These can be made in advance and stored in the freezer until ready to bake. Place the frozen croissants on a baking sheet (no need to thaw) and brush with egg wash. Bake for 35 to 40 minutes, if frozen. Enjoy!