Instructions

  1. Line 2 baking sheets with parchment paper or grease well.
  2. Steam asparagus in a steamer or on a rack in a skillet until tender-crisp, takes about 3 minutes.
  3. Immediately remove from pan and chill in cold water to stop cooking; pat dry and set aside.
  4. Roll out each pastry sheet to fit the baking sheet, place on prepared pans.
  5. Spread evenly with mustard, leaving 1 inch border around the edges.
  6. Arrange asparagus, side by side and alternating ends, on the mustard; sprinkle with cheese and pepper.
  7. In a small bowl, beat egg with milk; lightly brush over the pastry border.
  8. Bake in oven, rotating pans halfway through, until puffed and golden. Cheese should be bubbly in about 18 minutes.
  9. To serve: cut each tart into 6 pieces, serve warm or cold.