Melt the butter in a large pot over medium heat.
Add the diced onion and sauté until translucent, about 5 minutes.
Stir in the flour and cook for 1-2 minutes to create a roux.
Gradually whisk in the vegetable broth and beer until smooth.
Bring the mixture to a simmer and cook for 10 minutes.
Add the heavy cream and stir to combine.
Slowly add the grated cheddar cheese, stirring until melted.
Season with garlic powder, mustard powder, salt, and pepper.
Simmer the soup for another 5 minutes, stirring occasionally.
Serve hot with optional toppings like bacon and chives.