Melt butter in a medium pot over medium heat. Add chopped onion and sauté until soft and translucent, about 5 minutes. Add minced garlic and cook for another minute until fragrant.
Make the Roux:
Stir in the flour and cook for 2 minutes until lightly golden — this helps thicken the soup.
Add the Broth:
Gradually whisk in the chicken or vegetable broth, stirring constantly to prevent lumps. Simmer for 5–7 minutes until slightly thickened.
Incorporate Dairy:
Slowly pour in the milk and heavy cream, stirring continuously. Let the soup simmer on low heat for about 5 minutes until smooth and creamy.
Add the Cheese:
Remove from heat and stir in the shredded cheddar cheese until fully melted. Season with salt, pepper, and a pinch of nutmeg if desired.
Serve:
Ladle into bowls and garnish with toasted bread or extra shredded cheese.
