Given the task definition and input, reply with output. In this task, you will be presented with the directions of a recipe separated by "," and have to fill in the "___" which is a step that is missing from the recipe.

Thaw the pastry sheet at room temperature for 40 minutes or until it's easy to handle. Heat the oven to 400 degrees F. Line a baking sheet with parchment paper.,______,Arrange the asparagus on the pastry in a single layer. Sprinkle with the prosciutto, fontina and thyme.,Bake for 20 minutes or until the pastry is golden and the asparagus is tender.
Unfold the pastry sheet on a lightly floured surface. Roll the pastry sheet into a 10 x 14-inch rectangle. Place the pastry sheet onto the baking sheet. Brush the pastry sheet with the mustard. Fold in the edges of the rectangle about 1/4-inch and crimp with a fork to seal.