1. Preheat grill to medium-high.
2. Add garlic and red pepper to 2 tablespoons of olive oil and let sit for at least 1 hour.
3. Cook spinach in boiling salted water, just until it wilts (bout 2 minutes). Remove with a strainer and put under cold running water. Use your hand to squeeze out all possible moisture, then coarsely chop and set aside.
4. Prepare crust according to directions.
5. Lightly brush crust with plain olive oil. Sprinkle the spinach across the surface, leaving a 1" border of crust. Sprinkle on the garlic slices, then the mozzarella and finally the goat cheese crumbles. (Scatter on the optional mushrooms or shrimp at this stage.)
6. Cook according to directions.
7. Remove from oven and immediately drizzle the infused oil across the pizza. Let cool for 2-3 minutes, and then slice to serve.
Makes 1, 12" pizza or 2, 6" pizzas