Follow the package directions for thawing the pastry.
On a large sheet of parchment paper, roll a sheet of pastry out into a rectangle about 10 inches by 13 inches. Slide the sheet of pastry, parchment and all, onto a large baking sheet.
Roll the second sheet of pastry out on a sheet of parchment paper as before and slide it onto another large baking sheet. Place both sheets of pastry in the fridge and chill for 20 minutes.
Meanwhile, combine the honey mustard, jam, and whole grain mustard in a small bowl. Set aside.
Remove one of the pastry sheets from the fridge.
Brush the mustard mixture over the pastry, leaving a 3/4-inch border on all sides.
Sprinkle half of the shredded cheese over the honey mustard mixture, then sprinkle the diced ham over the cheese. Finish with the remaining shredded cheese and sprinkle with the Parmesan cheese.
Whisk the egg with the cream until well blended and brush around the border.Remove the remaining sheet of pastry from the fridge and place it over the ham and cheese-filled sheet. Press the edges together, then roll them inwards to make a crust all around the tart.
Brush the pastry all over with the egg wash.
Place the tart in the freezer for 10 minutes or chill it in the fridge for 20 minutes.
Position a rack in the center of the oven and preheat to 400 F.
Cut several vents in the top of the tart to allow steam to escape and bake it for 28 to 32 minutes, until golden brown. If it appears to be too dark, tent it with foil for the last 5 minutes or so.