Step 1

Preheat oven to 350 degrees F (175 degrees C). Lightly grease a 9x13 inch baking dish.

Step 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.

Step 3

Heat the oil in a saucepan over medium heat. Stir in the mushrooms, cook 1 minute, and set aside. Melt margarine in the saucepan. Mix in flour, garlic, and basil. Gradually mix in milk until thickened. Stir in 1 cup cheese until melted. Remove saucepan from heat, and mix in cooked pasta, mushrooms, spinach, and soy sauce. Transfer to the prepared baking dish, and top with remaining cheese.

Step 4

Bake 20 minutes in the preheated oven, until bubbly and lightly brown.