Savory Asparagus and Ham Tarts

SAVORY ASPARAGUS AND HAM TARTS
1 (8.65 oz.) sheet frozen puff pastry, thawed
Dijon mustard
1 ¼-oz. thinly sliced deli ham
1 c. shredded Gruyere or Swiss Cheese
12 thin spears fresh asparagus, trimmed, tossed with olive oil and seasoned with salt and pepper
1 egg yolk, beaten with 1 T. water

1. Preheat oven 400.
2. Line baking sheet with parchment paper.
3. Roll thawed puff pastry into 16×10” rectangle, then cut into thirds lengthwise.
4. Score ¼” border on each piece of pastry with tip of knife.
5. Spread thin layer of mustard inside border of pastries.
6. Divide ham among pastries, then sprinkle cheese on top of ham.
7. Arrange 4 spears in single layer over each pastry.
8. Brush border of pastries with egg wash.
9. Bake tarts until cheese melts and pastries are golden, 15-20 minutes.