Preheat the oven to 375 degrees. Gently place the pie crust into a 9-inch round pie pan or quiche pan. Pinch the rim decoratively and prick the crust with a fork. Bake the crust for 10 minutes. Pull it out and let it cool while you prepare the filling.
In a large bowl, whisk together the eggs, flour, nutmeg, salt and pepper. Whisk in the cream and then the milk.
In a separate bowl, combine the Swiss and blue cheeses and then sprinkle them into the prepared pastry shell. Sprinkle the red onion and walnuts over the cheese. Gently pour in the egg mixture to fill the pastry shell.
Place the filled pan on a baking sheet and bake the quiche for 35 to 40 minutes, or until the custard is just set. Watch the edges of the crust and cover with foil or a pie-crust cover if it's browning too much. Let the quiche rest for 8 to 10 minutes before slicing and serving.