Place a large pot over medium heat. Add 1 tablespoon of olive oil, swirl to coat until heated, and add sliced sausage. Cook, stirring occasionally, for about 5 to 7 minutes or until the sausage is browned. Remove sausage to a paper towel-lined plate, pour a bit more oil in the center of the pot if needed, and add minced garlic. Stir and cook for about a minute or until the garlic is fragrant and light golden.
Pour 4 cups chicken broth/stock into pot and stir in kale, bay leaf, and garlic powder. Increase heat to high and bring to a boil. Reduce to a simmer, cover, and cook for 5 minutes.
Place about one-third of the drained beans in a blender or food processor, along with the remaining 1 cup chicken broth/stock. Puree until smooth.
Once kale is tender, add pureed beans, remaining whole beans, and browned sausage to the pot. Season with dashes of hot pepper sauce, salt, and pepper, to taste. Stir and simmer for a few minutes until heated through. Remove bay leaf before serving. Stir crumbled feta into bowls of soup and/or garnish with grated Parmesan, if desired.
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Notes
I pulse the kale leaves (after removing tough stems) in my food processor (using the regular blade) until shredded (but not pureed). After adding the kale to the soup, I use the same food processor bowl (without cleaning it first) to puree the beans with the broth.