Preheat oven to 350 degrees.
Mix flour, xanthan gum, salt, and 1 1/2 Tbsp. pepper. Cut crisco into flour. Add 2 eggs and just enough ice cold water (about 1/4 c to 1/2 c.) to make like pie dough. Split dough into two pieces (2/3 and 1/3 split for crust). The small portion is for the top crust and larger portion is for the bottom. (This can all be done in a large KitchenAid mixer using the flat mixer blade, not the whisk.)
If dough is warm, wrap in plastic and place in refrigerator before rolling. Roll the larger portion 1/4" thick on parchment paper (or on plastic grocery store bag cut into two large pieces) and place it in 9x13 glass pan so it fits on the bottom and all sides. Peel off the parchment paper. (You can also line a 9x13" pan with non-stick foil and place in that)
For Cheese mixture:
Hand beat 3 eggs and mix grated cheeses and ham to make it moist. Add lots of black pepper to taste (about 1 1/2-2 Tbs.). No salt. (The KitchenAid can be used for this also using the flat mixer blade) Add cheese mixture to pan with crust in it and pat down evenly. This will rise about an inch during cooking and then recede.
For Top Crust:
Roll out the second dough (small portion) on parchment paper until about 1/4" thick. Top the pan with the cheese mixture and seal all the edges. Slit the top and brush with a beaten egg.
Bake until golden brown about 45 minutes to 1 hour. Let cool to room temperature before slicing or cheese will run out. This freezes well.