A slow-cooker potato soup where half the potatoes are mashed in the pot to thicken it, finished with cheddar off the boil and served under bacon, sour cream and green onions.
Twenty minutes of peeling and cubing, five or six hours on Low, and about half an hour of finishing. Eight servings.
Why This Recipe Works
- Russets, specifically. They are high-starch and floury, which is what lets half of them mash into a thickener — a waxy potato would stay in firm pieces and the soup would never take on body.
- Mashing only half is a texture decision, not a shortcut. It gives you a creamy base and recognisable chunks in the same spoonful, which is the whole point of a loaded baked potato soup.
- The cornstarch slurry uses cold water. Cornstarch tipped dry into hot soup seizes into lumps instantly; dispersing it in cold water first is the only way it thickens smoothly.
- Turning to High for the slurry and back down for the cheese is deliberate. Cornstarch needs heat to set; cheese needs the absence of it.
- Half the cheddar goes in and half goes on. The melted cup and a half becomes the soup; the remaining half cup stays visible on top as a garnish along with the bacon and sour cream.
Four Stages, Three Temperatures
This soup changes heat setting three times in seven steps, and each change exists for a reason. Cooking it all on one setting is how it ends up either thin or split.
Stage 1 of 4
Soften, on LOW
Steps 1–2 of 7
Potatoes, onion, garlic, five cups of broth, salt and pepper, for five to six hours until the potatoes are VERY tender. Very tender matters — a potato that still has bite will not mash in the next step.
- Load the cookerAdd the potatoes, onion, garlic, broth, salt and pepper to the slow cooker.
- Cook on Low until very tenderCover and cook on LOW 5 to 6 hours, until the potatoes are very tender.
Stage 2 of 4
Mash, off the clock
Steps 3–4 of 7
About half the potatoes crushed in the pot, deliberately leaving chunks, then the milk and cream stirred in. The mashed half is the body of the soup; the chunks are what make it a loaded baked potato rather than a purée.
- Mash about halfMash about half the potatoes in the cooker, leaving some chunks.
- Stir in the dairyStir in the milk and cream.
Stage 3 of 4
Thicken, on HIGH
Steps 5–5 of 7
Three tablespoons of cornstarch whisked with three of COLD water, stirred in, then fifteen to twenty minutes on High. Cornstarch needs real heat to activate, which is why the setting goes up here and only here.
- Thicken with the slurry on HighWhisk the cornstarch with the cold water, stir it into the soup, and cook on HIGH 15 to 20 minutes until thickened.
Stage 4 of 4
Melt, on LOW or WARM
Steps 6–7 of 7
Down to Low or Warm, then a cup and a half of cheddar stirred in until melted — and no boiling afterwards. Cheese proteins tighten and squeeze out fat above a simmer, which is what makes a cheese soup go grainy.
- Melt in the cheddar off the boilTurn to LOW or WARM and stir in 1 1/2 cups cheddar until melted. Do not boil after adding cheese.
- Top and serveServe topped with the remaining cheddar, bacon, sour cream and green onions.
Ingredient Notes
- Russet potatoes
- Three pounds, peeled, in one-inch cubes. Russets are the floury variety this depends on — the starch is what does the thickening once half of them are mashed.
- Shredded sharp cheddar, divided
- Two cups, split a cup and a half into the soup and half a cup over the top. Sharp rather than mild: against three pounds of potato and two cups of dairy, a mild cheddar simply vanishes.
- Cornstarch and cold water
- Three tablespoons of each, whisked together before they go anywhere near the pot. The water must be cold — this is the one non-negotiable detail of a slurry.
- Bacon, cooked crisp
- Eight slices, already cooked and crumbled before they meet the soup. They are a garnish and they need to stay crisp, which they will not do inside the pot.
- Whole milk and heavy cream
- A cup of each. Both go in after the mash, when there is no more long cooking to do — dairy added at the start of a five-hour Low cook is liable to split.
How to Make It
Load the cooker
Add the potatoes, onion, garlic, broth, salt and pepper to the slow cooker.
Cook on Low until very tender
Cover and cook on LOW 5 to 6 hours, until the potatoes are very tender.
Mash about half
Mash about half the potatoes in the cooker, leaving some chunks.
Stir in the dairy
Stir in the milk and cream.
Thicken with the slurry on High
Whisk the cornstarch with the cold water, stir it into the soup, and cook on HIGH 15 to 20 minutes until thickened.
Melt in the cheddar off the boil
Turn to LOW or WARM and stir in 1 1/2 cups cheddar until melted. Do not boil after adding cheese.
Top and serve
Serve topped with the remaining cheddar, bacon, sour cream and green onions.
Success Tips
- Cut the potatoes to an even inch so they are all very tender at the same moment.
- Whisk the cornstarch into cold water in a separate bowl, never straight into the crock.
- Mash roughly half and stop — the chunks are the point of this soup.
- Turn the heat down before the cheese goes in and add it in handfuls.
- Keep the bacon out of the pot so it stays crisp in the bowl.
Serving Ideas
In deep bowls with the toppings set out so people can load their own. Crusty bread if you want it, though the soup is substantial on its own.
Storage and Reheating
Refrigerate
Refrigerate up to 4 days. It thickens considerably as it chills — the starch setting — and loosens again with heat and a splash of milk.
Freeze
Not recommended. Potato goes grainy after freezing and a cream-and-cheese soup splits on thawing.
Reheat
Gently on the hob, stirring, with a little extra milk or broth. Do not let it boil, for the same reason you did not boil it after the cheese went in.
Frequently Asked Questions
Is this a casserole?
No — it is a soup, eaten with a spoon. The loaded baked-potato toppings sit on top of each bowl rather than being baked into a dish.
Why is it called 'baked' if nothing is baked?
The name describes the flavour combination of a loaded baked potato — cheddar, bacon, sour cream, green onion. The method here is a slow cooker throughout, and no potato is baked at any point.
My soup went grainy after the cheese.
It got too hot. Cheese proteins tighten and release fat above a simmer, which is why the recipe drops to Low or Warm first and says not to boil afterwards. Adding the cheese in handfuls rather than all at once also helps.
Can I use red or new potatoes?
They will hold their shape but they will not mash into a thickener, so the soup stays thin and brothy. Russets are what this method depends on.
