Easy Vegetable Ragu

Name: Easy Vegetable Ragu
Prep time: 15 min
Cook time: 36 min
Total time: 51 min
Cuisine: Italian
Ingredients: 1 tablespoon olive oil (extra virgin); 1 tablespoon butter; 1 celery stalk (finely chopped); 1 carrot (large, finely chopped); 4 garlic cloves (minced); 2 cups cherry tomatoes; 1 red bell pepper (diced); 3 cups cremini mushrooms (diced); 2 tablespoons tomato paste; 1 tablespoon Italian seasoning blend; 2 teaspoons fresh sage (chopped); 1¾ cups vegetable stock; 8 ounces whole wheat pasta; ½ cup reserved pasta water; salt and pepper (to taste)