Preheat the oven to 325 degrees F. Grease a 9-inch deep-dish pie plate with butter.
Heat the butter in a large skillet over medium heat. Remove the sausage from its casing and place in the skillet. Cook, breaking apart the sausage with a wooden spoon, until cooked through and fully browned, about 10 minutes. Remove to a paper-towel-lined tray and set aside.
Add the shallots to the same pan and cook until soft, about 2 minutes. Add the spinach, 1/4 teaspoon salt and 1/4 teaspoon pepper and cook until the spinach is tender and its water has evaporated, 5 to 7 minutes. Add the chopped sun-dried tomatoes and cook until heated through.
Add the sausage to the prepared pie plate and then top with cooked spinach mixture.
In a medium bowl, beat together the eggs, milk, 1/4 teaspoon salt and 1/4 teaspoon pepper until frothy, about 1 minute. Pour the egg mixture over the spinach and sausage. Place the circular piece of goat cheese in the center of the pie dish and arrange the oblong pieces around it like flower petals. Place the sun-dried tomato strips in between the goat cheese "petals."