Scatter flour on a large piece of parchment paper making sure to get a little on each side of the dough. Roll the pizza dough out on the paper in an oval shape. Make sure to roll and stretch the dough 2-inches longer and 2-inches wider than the crockpot. Use the edges of the paper to lower the crust into the crock.
Cook the pork sausage in a skillet over medium-high heat, breaking into small pieces with a wooden spoon. Add minced garlic the last few minutes of cooking.
Spread sauce over the bottom of the pizza crust. Then cover with cheese. Lift and stretch the sides of the dough so it extends past the cheese. Sprinkle the crumbled sausage over the cheese and then add the pepperoni (if using). Lift and stretch the sides of the crust again so it is above the edge of the toppings.
To catch excess moisture, cover the crockpot with a long piece of paper towel. Place the lid over the paper towel and pull it tight.
Cook the pizza for 2-3 hours on HIGH, or 4-5 hours on LOW When ready to serve, lift the pizza out of the crock by the edges of the parchment paper and sprinkle the top with parmesan cheese and parsley. Cut into 8 slices. Enjoy!