How to Make It
Preheat the oven to the hottest temperature, preferably 500°F. Place the pizza stone on the bottom shelf of the oven to preheat. In a bowl, combine 2 tablespoons of the olive oil with the garlic and let stand for 30 minutes. Mix the Fontina with the mozzarella in a separate bowl.
Heat the remaining 2 tablespoons of the olive oil in a large skillet and sauté onions until softened, about 10 minutes. Add the lamb, tomatoes, tomato paste, parsley, pine nuts, spices, 1/4 teaspoon of salt and 1/4 teaspoon of pepper. Cook slowly for 10 minutes. Add the lemon juice and mix well.
Cut the pizza dough in half and roll each piece out to a 9-inch round, 1/4 inch thick. Transfer the dough to a heavily floured pizza peel. Brush the dough to within 1/2 inch of the edge with the garlic oil. Sprinkle half of the mixed cheeses on the dough and top with half of the spiced lamb. Transfer the pizza to the stone and bake until golden and crisp, 8 to 10 minutes. Repeat to make the second pizza.