Set a pizza stone in the oven and heat the oven to 500° for 30 minutes. Light a grill or preheat a grill pan. Scoop the garlic from the top of the hummus into a small bowl and stir in the 3/4 cup of olive oil. Season with salt and pepper. Transfer 3 tablespoons of the garlic oil to a large bowl. Add the zucchini and toss to coat. Whisk the hummus into the remaining garlic oil and season with salt and pepper.
Working in 2 batches, grill the zucchini slices over high heat until they are lightly charred, about 5 minutes. Brush the zucchini lightly with some of the hummus and grill for 1 minute longer, turning once.
Lightly rub 2 sheets of parchment paper with oil. Stretch each ball of pizza dough into a 12-inch round on each sheet. Brush each round with one-fourth of the hummus and top with the zucchini. Slide 1 parchment sheet onto the hot stone and bake the pizza for about 8 minutes, until the crust is browned. Transfer the pizza to a work surface and drizzle with some of the remaining hummus. Cut into slices and serve. Repeat with the remaining pizza.