Sausage and Leek Casserole

Name: Sausage and Leek Casserole (Slow Cooker)
Prep time: 10 min
Cook time: 4 h
Total time: 4 h 10 min
Yield: 4 servings
Cuisine: British
Ingredients: 1 tbsp olive oil; 10 pork sausages; 2 large leeks, sliced; 2 cloves garlic, minced; 1 tsp dried mixed herbs; 1 tbsp Dijon mustard; 1 tbsp wholegrain mustard; 250 ml chicken stock; 3 tbsp crème fraîche; 1 tbsp fresh parsley, chopped; salt, to taste; black pepper, to taste; Mashed potatoes, for serving; Broccolini, for serving

This Sausage and Leek Casserole is a slow cooker take on classic British bangers and mash, combining pork sausages with caramelised leeks in a silky Dijon and wholegrain mustard sauce. It's a hands-off weeknight dinner that builds deep flavour without constant attention.

⚡Slow Cooker

🌍British 🏷️Sausage casserole 🏷️Sausage and leek 🏷️Slow cooker Comfort food

🏷️

🏷️Easy dinner

-0:00

boredoflunchonTikTok

Total

4h 10m

Servings

4

Difficulty

Easy

Est. Cost

$26–$43

Recipe Source

View original recipe

From TikTok · by boredoflunch

-0:00

boredoflunchonTikTok

Ingredients

1 tbsp olive oil
10 pork sausages
2 large leeks, sliced
2 cloves garlic, minced
1 tsp dried mixed herbs
1 tbsp Dijon mustard
1 tbsp wholegrain mustard
250 ml chicken stock
3 tbsp crème fraîche
1 tbsp fresh parsley, choppedoptional
salt, to taste
black pepper, to taste
Mashed potatoes, for servingoptional
Broccolini, for servingoptional

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Instructions

1
In a large pan or a hob-safe slow cooker insert, heat the olive oil over medium-high heat. Add the sausages and sear on all sides until browned.
2
Add the sliced leeks to the pot with the sausages and sauté for 2-3 minutes until they begin to soften.
3
Stir in the minced garlic, dried herbs, Dijon mustard, and wholegrain mustard. Season with salt and pepper.
4
Pour in the chicken stock and stir everything together to combine.
5
Cover the slow cooker and cook on low for 7-8 hours or on high for 4 hours.
6
Once cooked, stir in the crème fraîche until the sauce is smooth and creamy.
7
Garnish with fresh chopped parsley before serving.
8
Serve hot with buttery mashed potatoes and your favorite green vegetables.

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Tips & Notes

Pro tips

Brown the sausages in olive oil before adding to the slow cooker to develop a golden crust and deeper flavour in the sauce.
Add crème fraîche in the last 15 minutes of cooking to prevent it curdling; stir gently to combine.
Slice leeks thinly and rinse well between layers to remove trapped soil, which can grit the final dish.
Use a mix of Dijon and wholegrain mustard for complexity; the grainy texture adds visual appeal and subtle texture.

Substitutions

Pork sausages → chicken or turkey sausages (reduce slow cooker time by 30 minutes; check internal temperature reaches 165°F)
Crème fraîche → sour cream or Greek yoghurt (add in final 10 minutes to prevent splitting)
Chicken stock → vegetable stock or beef stock (beef will deepen the savouriness)
Dijon + wholegrain mustard → English mustard powder (1 tsp mixed with 1 tbsp water; sharper flavour)

Storage & make-ahead

Store leftovers in an airtight container in the fridge for up to 3 days. Reheat gently on the stovetop over medium heat, adding a splash of stock or water to restore sauce consistency.

Equipment

slow cooker · large frying pan (for browning sausages)

Common Questions

Can I cook this on the stovetop instead of a slow cooker?

Yes. Brown the sausages in a large pot, sauté the leeks until softened, add stock and mustards, then simmer covered for 20–25 minutes until the sausages are cooked through. Stir in crème fraîche at the end.

What's the best way to slice leeks for even cooking?

Cut leeks in half lengthwise, rinse between layers to remove grit, then slice into half-moons about ½ inch thick. This size cooks evenly and releases flavour into the sauce.

Can I prep this the night before?

Yes. Brown the sausages and prep all ingredients up to 4 hours ahead, then refrigerate in a sealed container. Add to the slow cooker cold; cooking time may increase by 30 minutes.

What if I don't have crème fraîche?

Use sour cream, Greek yoghurt, or heavy cream (stir in at the end to avoid curdling). Cream cheese thinned with a splash of stock also works.

How long will leftovers keep?

Store in an airtight container in the fridge for up to 3 days. Reheat gently on the stovetop over medium heat with a splash of stock to restore creaminess.