Preheat the oven to 425 degrees.
Cut the acorn squash in half and remove the pulp.
Cut the squash into wedges and place on a foil lined baking sheet.
Drizzle squash with olive oil, salt and pepper.
Roast squash until edges begin to brown, about 20 minutes.
Remove from oven, allow to cool slightly, and cut squash into bite size pieces.
While squash is roasting, in a small frying pan, add olive oil and red onions and cook over medium-low heat until the onions begin to caramelize.
Remove onions from pan and add pine nuts. Over low heat, toast pine nuts until golden brown.
Stretch pizza dough and place on cornmeal lined pizza stone.
Spread desired amount of pesto over dough.
Sprinkle squash, pine nuts, torn prosciutto, and onions over pesto.
Sprinkle with mozzarella cheese and dollop with ricotta cheese.
Bake in 425 degree oven for about 20 minutes or until the crust is golden brown.