Preheat oven to 400°. Spray a baking sheet with oil.
Lay puff pastry flat on the baking sheet.
Fold edges 1/2 inch inward and press down gently with a fork. Puncture the inside of each puff pastry square several times with a fork.
Layer 1/4 C of the shredded cheese over the pastry. Arrange asparagus evenly on top of the cheese. Sprinkle remaining cheese over the asparagus.
Mix egg and water. Brush edges of puff pastry with the egg wash.
Bake for 15-17 minutes or until the edges are golden brown.
Top with thinly sliced prosciutto by folding it somewhat.
Mix all sauce ingredients together. Drizzle honey mustard sauce across the tart.
Cut into 9 squares.