Source: Bon Appetit, October 2010
6 cups vegetable broth
3/4 cup polenta (coarse cornmeal)
3 tablespoons all purpose flour
3 tablespoons butter
2 garlic cloves, peeled, crushed
Coarse kosher salt
8 ounces spinach leaves (stems discarded)
Bring 6 cups broth to simmer in large saucepan; cover to keep warm. Whisk polenta and flour in heavy large pot. Add 1 cup hot broth; whisk over medium-high heat until smooth. Stir in butter and garlic; sprinkle lightly with coarse salt. Gradually add 5 cups hot broth by cupfuls. Boil gently over medium heat until polenta is tender and soup is creamy and thickened, whisking frequently and adding more broth to thin, if desired, about 25 minutes. Stir in spinach by handfuls; simmer until wilted, stirring often, 5 to 7 minutes longer. Season with more coarse salt and black pepper.
Ladle soup into 6 bowls and serve.