These individual puff pastry tarts are shaped to resemble small books. Placing the assembled tarts in the freezer for 2-3 minutes before transferring them to the oven ensures they will puff dramatically when baking. For another flavor option, top half of them with caramelized onions, crumbled blue cheese, and thinly sliced pears.
Topped with ripe tomatoes and Gruyere cheese, these puff pastry tarts are a sophisticated treat to serve at your story-themed shower. Served with a mixed greens salad, it's the perfect lunch.”
Preheat the oven to 375 degrees. Remove the puff pastry sheet from the package and unfold if necessary; let them stand at room temperature until pliable. Flour the work surface underneath the pastry so they don't stick, then roll each sheet into a slightly larger rectangle, about 11 by 13 inches. Using a pizza cutter or sharp knife, cut each piece of pastry into 6 smaller rectangles to resemble books. Transfer the pieces to baking sheets that have been lined with parchment paper or Silpats.
Assembly: To assemble the tomato tarts, spread a thin layer of mustard on 6 of the tarts, leaving a 1/2" rectangular border around the sides. Sprinkle the mustard with the shallots, then half of the grated cheese. Top each page with a few slices of the tomatoes in an overlapping pattern. Sprinkle the tomatoes with the thyme and a generous pinch of salt and grinding of pepper.
Beat the egg with a tablespoon of water. Brush the egg wash all over the rims of the pages. Place the sheet pans in the freezer for 2-3 minutes before placing them in the oven. Bake until the pastry pages are puffed and golden brown, about 18-22 minutes. Serve immediately or at room temperature.