fresh ricotta and red onion pizza

INGREDIENTS

• 2 quarts whole milk
• 2 cups buttermilk
• 2 tablespoons olive oil, divided
• 2 cups thinly sliced red onions
• 1 1/2 teaspoons golden brown sugar
• 2 tablespoons balsamic vinegar
• Pinch of dried crushed red pepper
• 1 cup fresh ricotta cheese
• 6 to 8 thin slices prosciutto (speck works as well)