Creamy Mushroom and Leek Pie

My tiny London apartment had the world's most unreliable radiator, and this mushroom and leek shepherds pie became my survival strategy during that particularly brutal February. The kitchen would fill with that earthy mushroom aroma while the potatoes bubbled away, and suddenly the cold didn't matter quite so much.

I once made this for a dinner party where my friend Sarah, a dedicated carnivore, went back for thirds and texted me the next morning asking for the recipe. Now whenever winter threatens to drag on forever, I know exactly what's bubbling in my oven.

Ingredients

• 900 g (2 lbs) Yukon Gold potatoes: These naturally creamy potatoes mash like a dream without becoming gluey, and their thin skins mean less prep work
• 60 ml (1/4 cup) whole milk: Room temperature milk incorporates more smoothly into hot potatoes, preventing that stubborn lumpy texture
• 50 g (3 tbsp) unsalted butter: Let this soften on the counter beforehand so it melts evenly into the potatoes
• 50 g (1/2 cup) grated Parmesan cheese: Optional but adds a subtle salty depth that makes the topping sing
• 2 tbsp olive oil: Extra virgin gives you that fruity base note for sautéing
• 1 tbsp unsalted butter: Combining butter with olive oil prevents the butter from burning over medium heat
• 2 large leeks: The white and light green parts are where all the sweet oniony flavor lives
• 3 garlic cloves: Freshly minced releases more oils than pre-chopped
• 500 g (1 lb) mixed mushrooms: A mix of cremini, button, and shiitake gives you layers of earthy flavor
• 2 medium carrots and 2 celery stalks: Dice these small so they melt into the filling rather than standing out
• 1 tsp fresh thyme and rosemary: These woody herbs hold up beautifully to the long cooking time
• 2 tbsp all-purpose flour: This is what transforms the liquids into that velvety sauce
• 240 ml (1 cup) vegetable broth: Use a good quality broth you would happily drink on its own
• 120 ml (1/2 cup) heavy cream: The finishing touch that makes the filling feel luxurious
• 1 tsp Dijon mustard: Just enough to brighten all those rich flavors
• 60 g (1/2 cup) frozen peas: Add these at the very end so they stay bright and sweet

Instructions

Get your oven warming and potatoes started:

Preheat your oven to 200°C (400°F) and get those potatoes into a large pot covered with cold salted water. Cold water start ensures even cooking, and about 15 to 20 minutes should give you fork-tender potatoes.

Mash into cloudlike perfection:

Drain those potatoes well and return them to the warm pot. Add the milk, butter, Parmesan if you are using it, and season generously with salt and pepper before mashing until everything is silky smooth.

Build your flavor foundation:

Heat the olive oil and butter in a large skillet over medium heat. Add those sliced leeks and let them soften for about 5 minutes until they are fragrant, then toss in the garlic for just one minute more.

Crowd in the vegetables:

Add the mushrooms, carrots, and celery to the pan. Sauté for 8 to 10 minutes until the vegetables have softened and the mushrooms have released all their liquid, concentrating that incredible flavor.

Thicken it all together:

Stir in the thyme and rosemary, then sprinkle the flour over everything and cook for 2 minutes while stirring constantly. Gradually pour in the vegetable broth, making sure to scrape up any browned bits from the bottom of the pan.

Create the creamy filling:

Add the cream and Dijon mustard, letting everything simmer for 5 minutes until the sauce has thickened beautifully. Stir in those frozen peas and season generously with salt and pepper before removing from heat.

Assemble and bake:

Transfer the filling to a 2-liter baking dish and spread the mashed potatoes evenly over the top. Use a fork to create ridges across the surface, which will get wonderfully crispy in the oven. Bake for 25 minutes until golden and bubbling, and if you want extra crispy peaks, broil for 2 to 3 minutes at the end.

The patience test:

Let the pie rest for 10 minutes before serving. This feels impossible when everything smells this good, but it helps the filling set slightly so each serving holds its shape beautifully.

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Last autumn I brought this to a potluck where it disappeared before anyone even touched the roast chicken. Three people asked if I would make it for their upcoming winter parties, and somehow I became the unofficial shepherd's pie person of my friend group.

Make It Ahead

This pie actually benefits from some downtime. You can assemble the whole thing up to 24 hours in advance and keep it refrigerated, then bake when you are ready. Just add about 10 extra minutes to the baking time if it is coming straight from the fridge.

Vegetable Swaps

The beauty of this recipe is how flexible the filling can be. I have added parsnips for sweetness, spinach for color, and even corn in the summer months. Just keep the total vegetable quantity roughly the same for the best results.

Freezing And Storage

This freezes remarkably well, either before or after baking. I often make two dishes and freeze one unbaked for those nights when cooking feels impossible. Just wrap it tightly and it will keep for up to three months.

• Thaw overnight in the fridge before baking
• Individual portions reheat beautifully in the microwave
• The filling gets even better after a day in the refrigerator

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There is something deeply satisfying about scraping that last bit of crispy potato from the corner of the dish. This is the kind of comfort food that makes even the longest winter feel a little more manageable.

Recipe FAQs

→ Can I substitute the Yukon Gold potatoes?

Yes, Russet or red potatoes can work well for a fluffy and creamy topping, though Yukon Gold offers a buttery texture naturally suited for mashing.

→ How do I ensure the filling is creamy and thick?

Sauté vegetables thoroughly before adding flour to create a roux, then slowly stir in vegetable broth and cream to develop a smooth, thickened sauce.

→ What herbs complement the mushroom and leek filling?

Fresh thyme and rosemary add earthy and aromatic notes that enhance the savory flavors of the filling.

→ Can this dish be made vegan?

Absolutely. Replace dairy ingredients with plant-based milk, vegan butter, and omit Parmesan or use a vegan alternative.

→ What vegetables can be added or substituted?

Carrots, celery, spinach, parsnips, or frozen peas all work well to add texture and nutrition to the filling.

→ How can I achieve a crispier potato topping?

After baking, broil the potato layer for 2-3 minutes until golden and slightly crispy on top.