Preheat over to 400 degrees. Chop onion and add to warm pan with one teaspoon oil and sauté until translucent for a few minutes. Chop one cup potatoes, mince two-three sprigs rosemary and add to onions. Chop eight slices bacon and add to onions mixture, stir well and cook a few minutes. Remove swiss chard leaves from stems, chiffonade three-four cups and add to onion mixture, season to taste, stir well and cook a few minutes. Whisk six eggs with one half cup fomage blanc cheese, season with salt and pepper, stir well and add to onion mixture. Let eggs cook for a few minutes until the bottom and sides begin to set then transfer to oven for fifteen minutes. Test frittata center with fork to confirm the center is cooked, then remove to cool and set up for five minutes before serving.