Place pie crust in deep pie dish. Sprinkle with sliced almonds. Top with Parmesan and bake at 350 degrees for 12 minutes
Melt butter in skillet with olive oil. Add onion and cook over medium low heat, stirring occasionally, for 15-20 minutes until caramelized.
Remove onions to a plate. Turn heat up to medium high and add prosciuto. Saute each side until it begins to crisp. Set aside.
Fill pie crust with onions, fruit, prosciutto and Gruyere. Beat eggs with buttermilk and season. Pour into pie crust. Top with reserved gruyere. Bake at 350 degrees for 34-45 minutes until quiche is set. Garnish with almonds if desired.