8 - ounces mushrooms, sliced
2 - teaspoons olive oil
1 - can (28-ounces) plum tomatoes, cut up
1 - can (6-ounces) low-sodium tomato paste
1/2 - teaspoon dried oregano
1/2 - teaspoon garlic powder
1/2 - cup white wine
1 - package (20 ounces) package of cheese-stuffed pasta shells

• In a skillet, sauté the mushrooms in the oil for about 5 minutes. 
  
• Transfer them to the 3 to 4-1/2 quart slow cooker.
• To the slow cooker, add the tomatoes, tomato paste, oregano, garlic and wine.
• Cover and cook on HIGH for 3-1/2 to 5 hours.
  
• Add the shells to the sauce, making certain to cover them with sauce.
• Cover and cook for about 1 hour or until the shells are thoroughly hot.