Preheat your oven to 350 degrees. Spray a pie dish with oil.
Cook the sausage in a large skillet over medium heat, breaking up until cooked, about 5 minutes.
Add the spinach and reduce heat to low, cook until wilted stirring occasionally, about 7 minutes. Drain spinach well.
Evenly spread the spinach sausage mixture in the prepared dish and top it evenly with the grated havarti and parmesan cheese.
Make the custard mixture by whisking together the milk, half and half, eggs, salt, black pepper, and the nutmeg.
Pour the custard into the dish and bake 35 to 40 minutes, until the center is set.
Cut the quiche into 6 pieces and serve.