For the topping:
Preheat oven to 400°F. Roll pizza dough out to a 10 x 15-inch rectangle at 1/4-inch thickness. Transfer to a lightly greased sheet pan. Combine next five ingredients together and brush evenly over pizza dough. Spread fontina cheese evenly over top. Stir the mozzarella and ricotta together in a small bowl and place small dollops over pizza. Cut one-inch tips off asparagus and reserve stems for another use. Spread tips over top and sprinkle with green onion. Season with salt and pepper. Cook in center rack of oven for 15 minutes or until all cheese is melted and lightly browned. Slice and serve warm.