Wash potato thoroughly and using a fork, poke the potato 3-5 times on each side.
Bake directly on oven rack at 400° for 90 minutes or until the skin is crunchy and the inside is soft. Seen post for details on how to know when your potato is done.
Remove and cut in half lengthwise, allow to cool for a few minutes. Reduce oven heat to 350° F.
Using a spoon, scoop out the potato and place potato flesh in medium size mixing bowl.
Add butter, sour cream, salt and pepper. Using a hand mixer, beat potato mixture until it's a thick dense mashed potato.
Chop prosciutto and add to bowl. Add Italian blend cheese & ¼ cup of Asiago Cheese. Mix by hand with a spoon or spatula.
Taste and add salt/pepper if needed.
Place potato skins on baking tray and stuff with potato mixture.
Top with remaining ¼ cup of Asiago cheese and ¼ cup of freshly grated Parmesan.
Bake at 350 degrees Fahrenheit for 30 minutes or until cheese is melted and golden brown.
Serve and Enjoy!
Initial Baking Time will vary depending on size of potato or the number of potatoes you are cooking at one time. I've found 90 minutes works perfectly for a 2lb potato and about 70-75 minutes for a 1lb potato.