Preheat oven to 350 degrees. Lightly grease an 8X8X2-inch baking dish and set aside.
Meanwhile, heat oil in a large skillet over medium-high heat. Add arugula and garlic and cook until arugula has wilted, about 4 minutes. Transfer arugula mixture to a bowl.
In the same skillet add the sausage and stir with a fork to break up lumps. Cook over medium heat until browned, about 7 minutes. Add the Fontina cheese, pepper, cilantro, arugula and garlic, stirring until well combined. Remove from heat and set aside.
In a medium bowl, whisk together eggs, cream, milk, salt and pepper. Set aside.
Place 8 bread slices in prepared baking dish in a single layer. Gently press 2 baguette slices onto each side of dish. Spoon the arugula mixture into baking dish. Drizzle the egg mixture over arugula mixture, making sure to coat all the bread slices well. Allow the bread slices to soak for 5 minutes.
Sprinkle Parmesan cheese evenly over on top of tart.
Bake tart until puffed and golden and center is set; about 50 minutes. Remove from oven and let rest on a cooling rack for 15 minutes before serving.