Step 1

Preheat the oven to 350 degrees F (175 degrees C). Bring a pan of lightly salted water to a boil. Add the pasta, and cook until tender, about 8 minutes.

Step 2

Crumble ground beef into a skillet over medium-high heat. Cook, stirring constantly until evenly browned. Drain excess grease, and stir in the tomato sauce, sour cream and thyme.

Step 3

Place the cooked pasta into the bottom of a 2 quart casserole dish. Pour the ground beef mixture over the pasta. Cover with a layer of spinach. Top with shredded cheese.

Step 4

Bake for 30 minutes in the preheated oven, until heated through and lightly browned on the top.