1. Heat olive oil in a large deep skillet over medium heat. Add onion, carrot, and celery and cook until vegetables are slightly softened, 5 minutes. Add 1 cup water, season with salt and pepper, cover and cook until tender, 10 minutes.
2. Meanwhile, finely chop sage, thyme, and garlic together. Stir chopped herb mixture and beans into vegetables.
3. Cook pasta according to package directions. After 5 minutes, stir in escarole and continue to cook, until shells are "al dente," 1 to 2 minutes more. Drain, reserving 1 1/2 cups pasta water.
4. Add pasta and escarole to the vegetables, tossing with some pasta water until creamy and coated. Stir in 3/4 cup cheese, season with more salt and pepper to taste. Serve with grated cheese and a dollop of tomato pesto if desired.
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