Preheat the grill to 450ºF and place a deep 12-inch cast iron skillet on the grill over direct heat. Close the grill and allow the cast iron skillet to heat up for 10-15 minutes.
While the skillet is heating up, roll the pizza dough out on a clean, lightly floured surface to about 12-inches in diameter to fit inside the skillet. Set the pizza dough aside.
Uncover the grill and add the Italian sausage to the hot skillet. Break the Italian sausage up into small pieces and allow it to cook. When the Italian sausage is fully cooked, carefully remove it from the skillet and set aside.
Add the thinly sliced garlic to the skillet and toss the garlic with the Italian sausage drippings (you may need to add some olive oil depending on how much oil was let off by the pork). Let the garlic sauté in the skillet until fragrant and lightly browned. Remove the garlic from the skillet and set aside.
Next, drizzle the olive oil into the skillet and transfer the rolled out pizza dough into the cast iron skillet. Place the skillet over direct heat and let the pizza dough cook for 4-5 (uncovered) minutes or until the bottom of the pizza dough is golden brown. Make sure to monitor closely so you don’t burn the bottom of the crust.
Move the skillet to indirect heat and assemble the pizza. Pour the pizza sauce over the pizza dough and spread the sauce out evenly over the pizza dough, leaving about 1-inch on the edges for the crust.
Sprinkle the Italian sausage crumbles and garlic slices over the tomato sauce. Top the other ingredients with the shredded mozzarella cheese.
Cover the grill and let the pizza cook over indirect heat for 20-30 minutes (checking after 10 minutes) or until the pizza dough is fully cooked and the cheese is melted and golden browned. If you have a smaller grill, turn the cast iron skillet so that the opposite side of the skillet is closer to the heat.
Remove the pizza from the skillet and transfer it onto a cutting board. Let the pizza rest for 5 minutes before slicing.
Top the pizza with fresh basil and enjoy.