Creamy Wisconsin beer cheese soup made with local cheddar and lager is a Midwestern vegetarian comfort classic. Rich, warming, and perfect for family dinners on cold winter nights.
Melt unsalted butter in a large heavy-bottomed pot over medium heat. Add chopped onion, carrot, and celery. Sauté for 6–8 minutes until vegetables are softened, stirring frequently to prevent browning.
Sprinkle all-purpose flour evenly over the vegetables. Stir constantly for 2 minutes, ensuring the flour is fully cooked and no raw patches remain.
Gradually pour in vegetable broth while stirring to prevent lumps. Increase heat to medium-high and bring the mixture to a gentle simmer; cook for 5 minutes until slightly thickened.
Add whole milk and lager beer, then reduce heat to medium-low. Let simmer for another 5–8 minutes, stirring occasionally, until the soup base is creamy and well blended.
Remove the pot from heat and slowly add shredded cheddar cheese, stirring continuously until fully melted and soup is smooth. Stir in mustard powder, Worcestershire sauce, salt, and pepper. Taste and adjust seasonings as needed.
Return soup to very low heat for 2–3 minutes if necessary to maintain serving temperature, but do not boil. Serve hot with your choice of toppings.