You will need:
1 large bunch kale (about 10 ounces)
1/4 cup cubed pancetta or sliced bacon (about 2 ounces)
4 cups warmed chicken or vegetable stock, divided
2 tablespoons olive oil
1/2 whole yellow onion, chopped
1/4 teaspoon salt
1 medium apple, cored and chopped
1/4 cup crème fraîche, mascarpone cheese, or plain yogurt
Freshly ground black pepper
Wash the kale and remove the bottom inch of stem. Chop roughly into 1-inch pieces.
In a large skillet over medium heat, sauté the pancetta for 1 minute or until just barely showing color. Add the kale and stir to coat with rendered fat. (Add a glug of olive oil if pancetta didn’t render enough fat to keep the kale from sticking to the pan.) Cook, stirring, until the kale begins to wilt, about 5 minutes. Add 2 cups chicken stock, lower heat to medium-low and cook, stirring occasionally, for about 10 minutes.
Transfer the mixture to a blender; or blend with an immersion blender. (Fill the blender no more than halfway; puree in two batches if necessary.) Puree, starting on the lowest speed, until smooth. (When working with hot liquids in a blender, it’s wise to hold down the lid with a kitchen towel in case some liquid escapes when the motor is running.) Puree the second batch if necessary. Pour into a large bowl and set aside.
In the same skillet over medium heat, heat the olive oil and cook the onions with the salt until the onions just barely show color, stirring for about 3 minutes. Add the chopped apples and cook, stirring occasionally, for 5 minutes, or until the apples soften and onions are translucent. Stir in the remaining broth.
Transfer the mixture to the blender, splitting into two batches if necessary. Puree until smooth.
Combine the pureed apple and onion mixture with the kale mixture, and whisk to combine. If soup seems too thick, add more stock or water until it reaches the desired consistency.