-
1
Cook bacon in a 6-quart heavy pot over medium heat, stirring occasionally, until crisp, then transfer with a slotted spoon to paper towels to drain, reserving 2 tablespoons fat in pot. (Add vegetable oil if your bacon is very lean and doesn't yield enough fat.)
-
2
Cook celery, carrot, and onion in fat in pot over low heat, covered, stirring occasionally, until softened but not browned, 10 to 12 minutes. Add cinnamon and cook, uncovered, stirring, 1 minute.
-
3
While vegetables are cooking, peel potatoes and coarsely chop. Peel and core 1 apple and coarsely chop.
-
4
Stir squash, potato, chopped apple, stock, 2 cups water, 1 teaspoon salt and 1/2 teaspoon pepper into onion mixture, then simmer, uncovered, stirring occasionally, until vegetables are very tender, 15 to 20 minutes.
-
5
Puree soup in 4 batches in a blender (use caution when blending hot liquids), then heat in cleaned pot over medium low heat, stirring occasionally. (Add additional 1/2 cup water to thin, if necessary.)
-
6
While soup is heating, cut enough of remaining apple into thin matchsticks (about 1 1/2-inches long) to measure about 1/2 cup.
-
7
Serve soup topped with sour cream, bacon, and apple matchsticks.
