First, roll out the puff pastry an extra inch. Now place on a parchment paper-lined sheet pan.
Leaving a 1 inch border, poke holes with a fork on puff pastry. This is so the middle does not rise during baking.
Next, spread Dijon mustard all over except the border. Now add Gruyere cheese and black pepper all over.
Now, in a bowl, mix the asparagus, tomatoes, 1 tsp black pepper, red pepper flakes, and salt.
Add the asparagus and tomatoes in rows to fill the puff pastry. Make sure to leave the 1 inch border uncovered.
Finally, bake the puff pastry pizza at 400 degrees 15-20 minutes. Check after 15 minutes to make sure it doesn't burn.
Enjoy!
