1½ cups whole milk
2 cups low-sodium chicken broth
2 tablespoons canola or grapeseed oil
4 tablespoons unsalted butter, divided
2 carrots, peeled and finely chopped
2 celery stalks, finely chopped
1 medium yellow onion, finely chopped
¼ fennel bulb, finely chopped
1 garlic clove, very finely chopped
1 dried bay leaf
¼ cup all-purpose flour
1 cup pilsner-style beer (such as Pilsner Urquell or Brooklyn Pilsner)
1 tablespoon Worcestershire sauce
1 pound mild cheddar, coarsely grated (about 4 cups; preferably orange Wisconsin cheddar)
¼ teaspoon kosher salt
½ teaspoon freshly ground black pepper
4 cups unseasoned plain popped popcorn
¼ teaspoon ground fennel seeds
1. In a medium saucepan set over medium heat, combine the milk and the chicken broth. Bring to a simmer, then reduce the heat to low to keep the mixture warm.
2. In a soup pot set over medium heat, add the oil and 2 tablespoons of the butter. Once the butter is melted, add the carrots, celery, onion, fennel, garlic and bay leaf. Cook, stirring frequently, until the vegetables are soft, about 8 minutes. Sprinkle in the flour and cook, stirring constantly with a wooden spoon, for 3 minutes.
3. Slowly pour in the warm milk-broth mixture, whisking constantly to avoid forming lumps. Whisk in the beer and bring the mixture to a simmer. Cook for 5 minutes, stirring frequently and monitoring the heat so the soup simmers but doesn't boil (boiling causes the soup to separate). Remove the bay leaf and stir in the Worcestershire sauce. While stirring constantly, gradually add the cheddar cheese, salt and pepper. Transfer about half of the soup to a blender and blend until smooth. Strain the soup through a fine-mesh sieve and into a clean soup pot set over medium-low heat to keep the soup warm; repeat with the remaining soup.
4. In a medium bowl, add the popcorn. In a medium saucepan set over medium heat, melt the remaining 2 tablespoons of butter. Add the ground fennel seeds and whisk to combine. Pour the butter over the popcorn and toss to combine.
5. Ladle the soup into serving bowls and serve topped with the seasoned popcorn.