Crockpot Broccoli Cheddar Soup

The butter and onion soften together in the saucepan before the slow cooker ever gets involved, and that small head start gives this Crockpot Broccoli Cheddar Soup a smoother, more…

By Ava
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November 14, 2026
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Reading time: 9 min

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The butter and onion soften together in the saucepan before the slow cooker ever gets involved, and that small head start gives this Crockpot Broccoli Cheddar Soup a smoother, more savory base. I used to skip that step and toss everything into the crock, but the onion stayed sharper and the flour was harder to whisk in evenly. Taking a few minutes at the stove gives the broth a clean start, without asking you to babysit the soup all afternoon.

Broccoli cheddar soup can turn into a bowl of uniform puree or a thin broth with vegetables floating in it. Here, I blend about half and leave the rest in tender pieces. The pureed broccoli adds body alongside the flour, while the intact florets make each spoonful feel like soup rather than sauce. Sharp cheddar brings a familiar tang, and a little dry mustard gives that cheese flavor a quiet lift. The finished bowl is creamy, full of broccoli, and thick enough to cling to the spoon.

Why Pureeing Only Half the Broccoli Gives This Soup Its Body

Blending all the vegetables would make a smooth soup, but it would also erase the texture that makes a slow-cooker bowl satisfying. Leaving some florets whole gives you tender bites of broccoli, while the portion you puree thickens the broth without needing extra flour or another thickener. The contrast is what keeps this soup from feeling heavy and one-note.

The order matters, too. The flour is whisked into the softened onion mixture first, then the broth goes in gradually. That creates a smooth base before it reaches the slow cooker, where there’s no practical way to whisk out flour lumps once the broccoli is in the pot. The slow cooker handles the long, gentle cooking; the saucepan handles the bit that needs active stirring. Together, those jobs give you a creamy base and vegetables that cook until tender without constant attention.

When you puree, aim for about half the soup rather than chasing a perfectly even texture. That leaves visible florets and shredded carrot among the creamy parts. If you prefer a completely smooth bowl, you can blend more, but the texture will be different from the chunky, spoonable version I make here.

What Sharp Cheddar, Dry Mustard, and the Flour Base Each Bring

• Broccoli florets — They provide the main vegetable flavor and the pieces you’ll keep in the finished soup. Cut or separate large florets into fairly even pieces so they soften at a similar pace. Fresh florets give the most predictable texture; frozen broccoli works in a pinch, though it tends to finish softer.
• Sharp cheddar — Its sharper, tangier taste stands up to the cream and broccoli. Freshly shredding a block gives the cheese a smoother melt than many pre-shredded bags, which contain coatings to keep the strands separate. A good store-brand block is fine; the sharpness matters more than choosing an expensive label.
• All-purpose flour — This thickens the broth before it goes into the slow cooker and helps give the soup a creamy body. Whisk it into the butter and onion until no dry patches remain, then add the broth gradually. For a gluten-free version, use a cup-for-cup gluten-free flour blend in the same quantity.
• Low-sodium chicken broth — It supplies the savory base without making it difficult to control the salt alongside the cheddar. A standard grocery-store carton works well here. For a vegetarian version, use low-sodium vegetable broth instead; the soup will taste a little less chicken-savory.
• Dry mustard powder — It sharpens the cheddar flavor without making the soup taste like mustard. Keep it dry rather than swapping in prepared mustard, which adds liquid and a different, more acidic taste.
• Heavy cream — It adds richness at the finish. It’s a better fit here than milk, which makes a thinner soup and is more likely to lose its smooth texture when heated with cheese.

From Smooth Onion Base to Melted Cheddar: The Slow-Cooker Sequence

Soften the Onion Before the Crockpot

Melt the butter in a medium saucepan over medium heat, then add the finely chopped onion. Cook for 4–5 minutes, stirring, until the pieces have softened; they shouldn’t be browned. Stir in the minced garlic and cook for 30 seconds, just until fragrant. If the garlic darkens, it can taste bitter, so keep it moving and don’t step away during this short stage.

Whisk a Lump-Free Broth Base

Sprinkle the flour over the onion mixture and cook for 1 minute, stirring constantly. Gradually whisk in the chicken broth, adding it in a steady stream so the mixture stays smooth instead of forming floury clumps. Bring it just to a simmer, then take it off the heat. The liquid should look evenly blended, with no dry flour at the bottom of the pan.

Let the Broccoli Turn Tender

Pour the broth mixture into a 6-quart slow cooker. Add the broccoli, shredded carrots, dry mustard powder, kosher salt, and black pepper, then stir to combine. Cover and cook on LOW for 4–5 hours or HIGH for 2–3 hours, until the broccoli is very tender. Check a larger floret with a fork; it should yield easily rather than stay firm in the center.

Blend for a Creamy Base with Pieces

Use an immersion blender to puree about half the soup, moving it through several areas of the slow cooker. Stop once part of the broth and vegetables look creamy and the rest still has clear broccoli pieces. Keep the blender head beneath the surface while it’s running to limit splashes. If you blend everything, the soup will be smooth rather than chunky.

Finish Gently with Cream and Cheddar

Set the slow cooker to WARM and stir in the heavy cream. Add the freshly shredded cheddar by handfuls, stirring until each addition melts before you add more. The cheese should disappear into the soup, leaving it creamy rather than stringy. Don’t let the soup boil once the cream and cheddar are in.

Useful Swaps for the Broth, Flour, and Cheddar

Questions That Come Up with Crockpot Broccoli Cheddar Soup

Crockpot Broccoli Cheddar Soup

Crockpot broccoli cheddar soup cooks low and slow until the broccoli is very tender, then gets partly blended for a creamy texture with tender pieces throughout. Freshly shredded sharp cheddar melts into the warm soup for a rich, cheesy finish.

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Prep Time 10 minutes mins

Cook Time 5 hours hrs 7 minutes mins

Total Time 5 hours hrs 17 minutes mins

Servings: 6 servings

Course: Lunch

Cuisine: American

Calories: 540

Ingredients Equipment Method Notes

Ingredients

  

• 4 tbsp unsalted butter
• 1 yellow onion medium, finely chopped
• 2 cloves garlic minced
• 0.25 cup all-purpose flour
• 4 cups low-sodium chicken broth
• 6 cups broccoli florets about 1.5 pounds
• 1 cup carrots shredded
• 0.5 tsp dry mustard powder
• 0.5 tsp kosher salt
• 0.25 tsp black pepper
• 1 cup heavy cream
• 12 oz sharp cheddar cheese freshly shredded

Equipment

• 1 6-quart slow cooker
• 1 immersion blender

Method

 

1. Melt the butter in a medium saucepan over medium heat.
2. Add the onion and cook for 4–5 minutes, stirring, until softened.
3. Add the garlic and cook for 30 seconds.
4. Whisk the flour into the onion mixture and cook for 1 minute, stirring constantly.
5. Gradually whisk in the broth until smooth and bring just to a simmer.
6. Pour the broth mixture into a 6-quart slow cooker.
7. Add the broccoli, carrots, mustard powder, salt, and pepper, and stir to combine.
8. Cover and cook on LOW for 4–5 hours or HIGH for 2–3 hours, until the broccoli is very tender.
9. Use an immersion blender to puree about half the soup, leaving some broccoli pieces intact.
10. Set the slow cooker to WARM and stir in the cream.
11. Add the cheddar by handfuls, stirring until melted; do not let the soup boil.

Notes

Add the freshly shredded cheddar by handfuls while the slow cooker is on WARM to help it melt smoothly. Refrigerate leftovers for up to 3 days; freezing is not recommended because the cream and cheese may separate. For a vegetarian variation, use vegetable broth instead of chicken broth.