Wild Mushroom–Green Olive Gratin Toasts with Preserved-Lemon Crème Fraîche + Quick Dressed Arugula

Name: Wild Mushroom–Green Olive Gratin Toasts with Preserved-Lemon Crème Fraîche + Quick Dressed Arugula
Prep time: 20 min
Cook time: 25 min
Total time: 45 min
Yield: 6 servings
Ingredients: 450 g Mixed wild mushrooms (oyster, maitake, chanterelle, or cremini), torn/sliced; 1 tsp Kosher salt; 1/2 tsp Black pepper; 2 tbsp Unsalted butter; 1 tbsp Olive oil; 2 Shallots, finely sliced; 2 cloves Garlic, finely grated or minced; 1 tsp Fresh thyme leaves; 120 ml Dry white wine or dry vermouth; 120 ml Crème fraîche; 1 1/2 tsp Dijon mustard; 1 tbsp Preserved lemon peel, finely chopped; 70 g Castelvetrano olives, chopped; 90 g Gruyère, coarsely grated; 25 g Parmesan, finely grated; 35 g Panko breadcrumbs; 1 tbsp Lemon juice; 60 g Arugula; 2 tbsp Extra-virgin olive oil; 1 1/2 tbsp Sherry vinegar or white wine vinegar; 1/2 tsp Honey; 8 slices Baguette or country loaf, sliced; 1 clove Garlic clove, halved (for rubbing toast)

This is my winter bistro bite when I want briny + bright without doing the whole seafood-tower song and dance: jammy wild mushrooms baked under a bubbly, cheesy gratin lid, spooned over garlicky toast. I finish it like a Californian who trained in Paris—preserved lemon, a little mustardy snap, and a quick, peppery salad right on top so every bite feels lifted.

Marguerite Lavigne

February 24, 2026

Prep: 20 minutes

Cook: 25 minutes

medium

appetizersnack

wild mushroomsgratinbriny-brightwinter gathering+1

Save a copy to your collection for editing

Ingredients

450 g Mixed wild mushrooms (oyster, maitake, chanterelle, or cremini), torn/sliced(Aim for a mix of textures; avoid washing—brush/trim instead)
1 tsp Kosher salt(Plus more to taste)
1/2 tsp Black pepper
2 tbsp Unsalted butter(Because we’re civilised)
1 tbsp Olive oil
2 Shallots, finely sliced
2 cloves Garlic, finely grated or minced
1 tsp Fresh thyme leaves(Or 1/2 tsp dried)
120 ml Dry white wine or dry vermouth(Natural wine is welcome at my house)
120 ml Crème fraîche(Sour cream works in a pinch)
1 1/2 tsp Dijon mustard
1 tbsp Preserved lemon peel, finely chopped(Rinse if very salty; substitute 1 tsp lemon zest + 1 tsp lemon juice)
70 g Castelvetrano olives, chopped(Or any buttery green olive)
90 g Gruyère, coarsely grated(Comté works too)
25 g Parmesan, finely grated
35 g Panko breadcrumbs(For the gratin crunch)
1 tbsp Lemon juice(Plus more to taste)
60 g Arugula(Or baby mustard greens)
2 tbsp Extra-virgin olive oil(For dressing + finishing)
1 1/2 tbsp Sherry vinegar or white wine vinegar
1/2 tsp Honey(Just to round the acid)
8 slices Baguette or country loaf, sliced(About 1.5 cm thick)
1 clove Garlic clove, halved (for rubbing toast)

Instructions

1
Heat the oven to 220°C / 425°F. Place 4–6 small gratin dishes (or one 20 cm / 8-inch baking dish) on a sheet pan for easy handling.
5 min
Tip: If you’ve got convection, use it—this is a gratin, not a spa day.
2
Toast the bread: brush 8 slices Baguette or country loaf, sliced lightly with 1 tbsp Olive oil, bake 6–8 minutes, flipping once, until crisp and golden. While hot, rub with 1 clove Garlic clove, halved (for rubbing toast). Set aside.
8 min
Tip: Garlic-rubbed toast is the bistro trick that makes people think you tried harder than you did.
3
Cook the mushrooms (properly): heat a large skillet over high heat. Add 1 tbsp Olive oil and 2 tbsp Unsalted butter. Add 450 g Mixed wild mushrooms (oyster, maitake, chanterelle, or cremini), torn/sliced and 1/2 tsp Kosher salt; spread them out and let them sear without stirring for 2 minutes. Toss, then continue cooking until deeply browned and the pan is mostly dry, 6–8 minutes more.
10 min
Tip: If your mushrooms are steaming, your pan is too crowded—work in batches if needed.
4
Add 2 Shallots, finely sliced, 2 cloves Garlic, finely grated or minced, and 1 tsp Fresh thyme leaves; cook until the shallots soften and turn glossy, about 2 minutes. Pour in 120 ml Dry white wine or dry vermouth and boil hard until reduced by about half, 2–3 minutes.
5 min
Tip: That quick reduction is your ‘sauce’—all the flavor, none of the heavy cream nap.
5
Turn off the heat. Stir in 120 ml Crème fraîche, 1 1/2 tsp Dijon mustard, 1 tbsp Preserved lemon peel, finely chopped, and 70 g Castelvetrano olives, chopped. Taste and adjust with 1/2 tsp Black pepper and 1 tbsp Lemon juice if you want it brighter.
2 min
Tip: You’re balancing earthy (mushroom) with briny (olive) and bright (lemon). Trust your tongue.
6
Assemble the gratin: divide mushroom mixture into dishes. Toss 90 g Gruyère, coarsely grated, 25 g Parmesan, finely grated, and 35 g Panko breadcrumbs together, then sprinkle evenly over the top. Drizzle with a little 2 tbsp Extra-virgin olive oil.
5 min
Tip: A little oil on the crumbs = the kind of crunch people fight over.
7
Bake until bubbling and deeply golden, 10–12 minutes. If you want extra color, broil for 30–60 seconds at the end—watch like a hawk.
12 min
Tip: Gratins go from ‘perfect’ to ‘why is it black?’ in one sip of wine.
8
Meanwhile, dress the greens: whisk 1 1/2 tbsp Sherry vinegar or white wine vinegar, 1 tbsp Lemon juice, 1/2 tsp Honey, 2 tbsp Extra-virgin olive oil, and a pinch of salt. Toss with 60 g Arugula right before serving.
3 min
Tip: Dress at the last second so it stays perky, not sulky.
9
Serve: put garlic toast on each plate, spoon on (or tuck beside) the bubbling mushroom gratin, and crown with a small tangle of dressed arugula. Finish with a final squeeze of lemon if you like living deliciously.
2 min
Tip: The greens aren’t a side—they’re the bright, peppery ‘reset’ between bites.

Chef's Notes

This one reminds me of a February night in Oakland when it was raining sideways and I needed something that felt like a Paris bar snack—warm, cheesy, deeply savory—but with California energy. The preserved lemon is my little sunbeam, and the arugula salad on top is non-negotiable: it keeps the whole thing flirtatious instead of sleepy. Wine pairing: a salty, citrusy skin-contact white or a light chillable red (Gamay, Trousseau) that won’t bully the mushrooms.

Frequently Asked Questions

How long does Wild Mushroom–Green Olive Gratin Toasts with Preserved-Lemon Crème Fraîche + Quick Dressed Arugula take to make?

Wild Mushroom–Green Olive Gratin Toasts with Preserved-Lemon Crème Fraîche + Quick Dressed Arugula takes about 45 minutes total. That includes 20 minutes of prep and 25 minutes of cooking.

How many servings does this recipe make?

This recipe makes 6 servings.

What skill level is needed for Wild Mushroom–Green Olive Gratin Toasts with Preserved-Lemon Crème Fraîche + Quick Dressed Arugula?

This recipe is rated medium — it's intermediate, requiring some cooking experience.

What ingredients do I need for Wild Mushroom–Green Olive Gratin Toasts with Preserved-Lemon Crème Fraîche + Quick Dressed Arugula?

The main ingredients are: Mixed wild mushrooms (oyster, maitake, chanterelle, or cremini), torn/sliced, Kosher salt, Black pepper, Unsalted butter, Olive oil, Shallots, finely sliced, Garlic, finely grated or minced, Fresh thyme leaves, Dry white wine or dry vermouth, Crème fraîche, Dijon mustard, Preserved lemon peel, finely chopped, Castelvetrano olives, chopped, Gruyère, coarsely grated, Parmesan, finely grated, Panko breadcrumbs, Lemon juice, Arugula, Extra-virgin olive oil, Sherry vinegar or white wine vinegar, Honey, Baguette or country loaf, sliced, Garlic clove, halved (for rubbing toast).

What type of meal is Wild Mushroom–Green Olive Gratin Toasts with Preserved-Lemon Crème Fraîche + Quick Dressed Arugula?

Wild Mushroom–Green Olive Gratin Toasts with Preserved-Lemon Crème Fraîche + Quick Dressed Arugula is categorized as: appetizer, snack.

Chat with Marguerite Lavigne