Pasta with creamy sweet potato sauce

1 large sweet potato
2/3 cup 2% milk
2 cups uncooked penne pasta
1 Tablespoon pine nuts
1 teaspoon rubbed sage
1 Tablespoon butter
1 garlic clove, minced
1 teaspoon olive oil
3/4 teaspoon salt
1/4 teaspoon pepper
1/2 cup shredded Parmesan cheese
Additional shredded Parmesan cheese, optional
Scrub and pierce sweet potato. place on microwave safe plate. Microwave, uncovered, on high for 10-12 minutes or until tender, turning once. When cook enough to handle, remove and discard the skin. Place the potato in a large bowl and mash with milk.

Cook pasta according to package directions.. In a large skillet, saute pine nuts and sage in butter until pine nuts are toasted. Remove from pan and set aside.

In the same skillet, saute garlic in oil for 1 minute. Stir in the sweet potato mixture, Drain pasta reserving 3/4 cup cooking water; add to sweet potatoe mixture. Stir in cheese, pine nut mixtue and reserved cooking water. Sprinkle with additional cheese if desired.