1. Heat oven to 325 degrees F.
2. Melt butter in 8-inch ovenproof nonstick skillet. Add onion and cook over medium-high heat until onions start to brown, about 7 to 8 minutes, stirring to prevent burning.
3. In a large bowl or measuring cup, whisk together eggs, smoked turkey, half-and-half, 1/2 of the smoked Gouda, salt, black pepper, nutmeg and parsley.
4. Add egg mixture to skillet and cook 7 to 8 minutes until edges are just set. Gently stir the middle halfway through cooking.
5. Sprinkle remaining cheese over the top of the frittata. Place skillet in oven and bake at 325 degrees F for about 30 minutes or until completely set.
6. To serve, gently slide the frittata onto a serving plate and slice into 4 wedges. Serve with a green salad and low-carb or carb-free dressing, if desired. Makes 4 servings.