For the dough: Sprinkle the yeast over 3 cups warm (not lukewarm) water. Let stand for a few minutes.
In a mixer, combine the flour and salt. With the mixer running on low speed (with a paddle attachment), drizzle in the olive oil until combined with the flour. Next, pour in the yeast/water mixture and mix until just combined and the dough comes together. (The dough will be sticky.) Form the dough into a ball.
Coat a separate mixing bowl with a light drizzle of olive oil and toss the dough in the olive oil to coat. Cover the bowl tightly with plastic wrap and set it aside for 1 hour to rise. Then put it in the fridge to chill for 2 hours or longer. (The dough is much easier to work with when very cold.)
For the mushroom version: Add the olive oil to a pan with the heat on medium and saute the garlic and onions for about a minute. Add the mushrooms and thyme and saute for 3 minutes. Add the white wine and reduce for a couple of minutes until most of the liquid is gone. Season with salt and pepper. Let cool to room temperature.
For the meat version: Crumble the Italian sausage into a skillet with some olive oil and brown until cooked through, 5 minutes. Let cool.
When you are ready to make the pizza pockets, take half the dough and roll it out into a large rectangle. Cut into 18 rectangles with a rectangular cutter. Put 9 of the rectangles onto a baking sheet and top them with the fillings for the meat version: some marinara sauce, mozzarella, sausage, pepperoni and Canadian bacon. Lay the other 9 rectangles on top and crimp the edges with a fork. Brush with the beaten egg. Put into the freezer to flash-freeze for 30 minutes.
Repeat with the other half of the dough and the fillings for the mushroom version: some mozzarella, goat cheese and the sauteed mushrooms.
When the pockets have been flash-frozen, transfer to ziptop bags and store in the freezer.
When ready to cook, place on a baking sheet and bake at 450 degrees F for 10 to 12 minutes.