Slice onion and and stack slices on a square of foil with a pat of butter, a drizzle of Olive oil, S & P. Bring sides up to form a tight packet and roast at 400 for 1 hour.
Slice the top of garlic head off exposing the cloves. Place garlic on a square of foil, drizzle with olive oil and season with salt & pepper. Bring foil sides up to enclose the garlic. Roast at 400 for 1 hour along side of onion packet
Stretch dough into a crust. drizzle with olive oil and sprinkle with kosher salt and pepper. Bake crust 5-7 minutes until just starting to brown.
Remove from oven.
Spread garlic [just hold the head and squeeze and the soft garlic will slide out and toss away the papery shell] evenly over the crust.
Then add the onions making an even layer.
Microwave apple pieces in a microwave safe dish for 1 minute, just to soften.
Top crust with Proscuitto and apple.
This can hold in the fridge until you are ready to finish baking at 400 for about 10 more min. until crust is golden and toppings are starting to brown.