Microwave the potatoes Place cubed potatoes in a glass dish and microwave on high for 7–10 minutes, until just tender.
Make the roux In a large pot over medium-high heat, melt the butter. Whisk in the flour until smooth.
Add milk and thicken Gradually pour in the milk, whisking constantly. Bring to a gentle boil, then reduce heat and simmer 5–10 minutes, until the mixture thickens.
Combine potatoes and onions Stir in the drained potatoes and chopped onion. Cook 5 more minutes, until the onion softens.
Finish with sour cream and cheese Remove from heat and stir in sour cream and cheddar until melted and smooth. Season with salt and pepper.
Serve warm Ladle into bowls and garnish with extra cheese, chopped green onions, or crumbled bacon if desired.
Tips & Variations
For extra smokiness, stir in crispy bacon bits or chopped ham.
Swap half the milk for chicken broth for a lighter base.
Add chopped chives or green onions on top for a fresh bite.
Make it ahead: store in the fridge for up to 3 days and reheat gently, adding a splash of milk if it gets too thick.
