1. Preheat oven to 350 degrees F (175 degrees C). Lightly grease a 9×13 inch baking dish.
2. Bring a large pot of lightly salted water to a boil. Place pasta in the pot, cook for 8 to 10 minutes, until al dente, and drain.
3. Heat the oil in a saucepan over medium heat. Stir in the mushrooms, cook 1 minute, and set aside. Melt butter in the saucepan. Mix in flour, garlic, and basil. Gradually mix in cream until thickened. Stir in 1 cup Colby and 1 cup mozzarella cheese until melted. Remove saucepan from heat, and mix in cooked pasta, mushrooms, spinach, (Chicken optional) and soy sauce. Transfer to the prepared baking dish, and top with remaining mozzarella cheese.
4. Bake 20 minutes in the preheated oven, until bubbly and lightly brown.
5. Variation: Add 2 Cups of shredded rotisserie chicken to for protein lovers.