Introduction: Italian Meatball Pie. The ultimate comfort food - hot meatball sub, dripping with rich, savory tomato sauce and lots of melted cheese - baked into a tender bread crust pie. Can food possibly get any better than this? Step 1: What You'll Need:. (Note: This recipe makes a large enough pie to feed 8 people.)
Dough:
 - 1 tbsp. (1 pkg.) active dry yeast
 - 1/3 c. warm water (105-115 degrees F)(see note in step 2)
 - 1 1/3 c. warm water
 - 2 tbsp. sugar
 - 1/2 tbsp. salt
 - 1 1/2 tbsp. shortening
 - 4 to 5 cups all-purpose flour
Filling:
 - 1 1/2 lb. ground beef
 - 1/2 c. fresh bread crumbs(see note in step 3)
 - 1/2 c. grated parmesan cheese
 - 1 egg
 - 1 1/2 tsp. dried oregano
 - salt and pepper
 - 2 c. (500ml) store-bought or homemade tomato sauce
 - 2 c. grated mozzarella cheese
 - 3 tbsp. butter
 - 3 cloves garlic, minced Step 2: Making the Bread Dough Crust. Dissolve the yeast in the 1/3 c. warm water. (Use a thermometer to check the heat of your warm water, so that you don't kill the yeast with heat. This will ensure a light and tender bread dough crust.)
Pour the dissolved yeast into a large bowl, along with the remaining 1 1/3 c. warm water, sugar, salt, shortening and 2 cups of the flour. Using an electric mixer, mix the dough until smooth. Using a spoon, add in as much of the remaining 3 cups of flour needed to make the dough easy to handle, and not too sticky.
Turn the dough out onto a lightly floured surface; knead the bread dough until smooth and elastic, about 10 minutes. Return dough to bowl and spray with a little oil. Turn dough over and spray with a little more oil. This will prevent the dough from sticking to the bowl. Cover the dough with a clean kitchen towel, and let rise in a warm place* for 1 hour, until dough doubles.
(* a warm place can be on top of your fridge, on the stove while preheating, in a sunny window, on top of a computer monitor, anywhere that is a little warmer than room temperature) Step 3: Preparing the Meatballs. In a bowl, mix together the ground beef with the fresh bread crumbs*, parmesan cheese, egg, oregano, and salt and pepper to taste. 
Using a 1 1/2-inch ice cream scoop, or your hands, divide meat into meatball-sized portions, placing them onto a plastic cutting board. Once the meat is divided, roll the pieces into nice, round meatballs. 
Place the meatballs into a large, non-stick frying pan with a little oil. Cook meatballs over medium-high heat until browned on the outside. 
Pour 1 c. of the tomato sauce into the pan, reduce heat and let meatballs simmer, covered, for about 10 minutes. This will finish cooking the inside of the meatballs, as well as infuse them with tomatoey goodness.
(* to make fresh bread crumbs, place a torn-up slice of bread into a food processor  and pulse until you get crumbs. One slice of bread makes about 1/2 cup of bread crumbs) Step 4: Rolling Out the Crust. Dump the risen dough onto a floured counter and divide into 2/5 and 3/5 pieces. Roll out large half of dough large enough to cover the inside of a 10" (25 cm) pan* with a 1" (2.5 cm) overhang. Place into the pan and press into corners.
Roll out the smaller piece of dough into a 12" by 12" (30x30 cm) square and cut into 1-inch strips. These strips will be used to make a lattice top to the pie once it is filled.
(* I suggest using a 10" springform pan, which will provide extra support when the crust rises during baking. I used a quiche pan, which also worked well, but the crust overhang drooped slightly over the edges during baking.) Step 5: Assembling and Baking. Place the meatballs evenly into the bread dough crust. Pour extra 1 c. of tomato sauce over meatballs. Top the meatballs with the grated mozzarella cheese. 
Lay the dough strips in a grid pattern over the top of the pie, weaving each piece into the others to form a lattice top. Use a pair of kitchen shears to trim the edges of the dough to no longer than 1 inch past the edge of the pan.
Using water and your fingers, seal the edges of the pie closed by rolling the edge of dough over on top of itself, like the crust of a pizza.
In a small bowl, mix the butter and minced garlic, and heat for 30 seconds in the microwave. Using a pastry brush, brush the top crust of the pie with the melted garlic butter.
Preheat the oven to 350 degrees F. Cover the pie with a clean kitchen towel and let the dough rise again, about 20 minutes.
Place the pie in the oven and bake for 30 minutes, until the crust is golden brown. Now the hardest part: let the pie rest for 15 minutes before cutting into its deliciousness.  Step 6: Eating the Pie!. There you have it - one ooey-gooey, cheesy and delicious, hot-meatball-sub in a pie dinner. Serve up a nice big slice of this pie with a cesar salad and a dish of olive oil and balsamic vinegar, for dipping all the extra bread crust pieces in! Yummy!