Whisk together the eggs, creme fraiche, parsley, half of the smoked Gouda, and season with 1/4 teaspoon salt and 1/4 teaspoon pepper.
In a 12-inch nonstick oven-proof skillet, heat the oil over medium-high heat. Cook the sausage until starting to brown and almost cooked through. Add the potatoes and cook for 2 minutes more. Add the onion and bell pepper and cook, stirring occasionally, until starting to brown, 3 to 4 minutes.
Remove from the heat and pour the egg mixture over the top, stirring to distribute the vegetables. Sprinkle with the Monterey Jack and then the remaining smoked Gouda. Bake until the center is set, 12 to 14 minutes. Run a spatula around the edges of the frittata and carefully slide onto a serving platter.