The French savoury loaf cake is the most useful thing in the aperitif repertoire, and this Breton version is built on buckwheat, smoked trout and seaweed butter. Buckwheat flour and corn starch give a light, slightly earthy crumb, the trout goes in as cubes, and melted Bordier Seaweed Butter carries the whole thing. It takes about fifteen minutes to mix and thirty in the oven, and it is as good cold the next day as it is warm from the tin.
At a glance
- Difficulty: Easy
- Serves: 6
- Active time: About 15 minutes
- Cook: 20 to 30 minutes at 180°C (350°F, gas mark 6)
- Key ingredient: 80 g (1/3 cup) Bordier Seaweed Butter
Why this works
Every ingredient here is Breton, and they were all built for each other. Buckwheat, ble noir, is the grain Brittany grows and turns into galettes. Seaweed butter is Bordier's first flavoured butter, made in 1986 after a meal with friends, with iodised seaweed folded into butter churned by hand on a wooden malaxeur. Smoked trout sits between the two. The butter's salinity pulls the trout's smoke toward the sea instead of toward the campfire, and the buckwheat's mineral, almost bitter edge keeps the whole loaf from tasting like a rich snack.
Structurally this is a French cake sale, which is closer to a quick bread than to anything sweet. The corn starch is there on purpose: buckwheat has no gluten, so it cannot build structure on its own, and the starch lightens the crumb rather than letting it turn dense and gummy. Eggs and baking powder do the lifting, and the melted butter coats the flour so the crumb stays tender for days. That is also why the butter goes in melted rather than creamed. You are not aerating anything, you are enriching it.
Ingredients
Buckwheat flour and corn starch are equal by weight. Have the butter melted and the trout cubed before you start mixing.
| Ingredient | Metric | US |
|---|---|---|
| Trout smoked over beechwood | 100 g | 3 1/2 oz |
| Bordier Seaweed Butter, melted | 80 g | 1/3 cup (about 2 3/4 oz) |
| Buckwheat flour | 60 g | 4 tbsp |
| Corn starch, sifted | 60 g | 4 tbsp |
| Baking powder | 1 packet | 1 packet |
| Whole eggs | 3 | 3 |
| Milk | 10 cl | 6 3/4 tbsp (a scant 1/2 cup) |
| Arugula | 1 bunch | 1 bunch |
| Cumin seeds | 2 pinches | 2 pinches |
Method
Step 1: Mix the batter and fold in the trout
Heat the oven to 180°C (350°F, gas mark 6). Tip the buckwheat flour and corn starch into a large bowl and stir in the baking powder. Make a well in the centre and work in the whole eggs, the milk and the melted seaweed butter. Cut the smoked trout into cubes. Rinse the arugula, then chop it finely. Fold both into the batter. Add the cumin seeds, salt and pepper.
Step 2: Bake and cool
Grease a loaf tin and pour in the batter. Bake for 20 to 30 minutes. Let it cool, then serve either warm or cold.
Tips from our kitchen
- Let the melted butter cool before it meets the eggs. Straight off the heat it will scramble them and you will see specks in the crumb. Melt it first, then cube the trout and chop the arugula while it comes down to just warm.
- A French packet of baking powder is about 11 g, which is roughly 1 tablespoon of the US kind. Bordier does not spell this out, so that figure is our guidance rather than theirs. If you are using a 7 g sachet, one and a half is close enough.
- Squeeze the arugula dry after rinsing. Wet leaves add water the batter has not accounted for, and this loaf has no gluten to hold it together. Spin it or wring it in a towel before chopping.
- The stated times do not quite agree. Bordier's header says 30 minutes while the method says 20 to 30. Start checking at 20 with a skewer in the centre, and pull the loaf when it comes out clean. Buckwheat browns early, so colour is not a reliable signal here.
- Season the batter properly. Salt and pepper appear in the method but not in the ingredient list. The seaweed butter and the smoked trout both bring salt, so taste is the wrong guide with raw egg in the bowl. A generous half teaspoon of fine salt for the whole batter is a safe starting point.
- Bruise the cumin seeds. A few seconds in a dry pan or a light crush in a mortar wakes them up. Whole and untoasted they mostly go unnoticed against the smoke and the seaweed.
How to serve it
Cut it into thick slices for the table or into cubes for an aperitif, with a bowl of creme fraiche and lemon alongside. It travels well, which makes it a genuinely good picnic loaf, and a cold slice with a green salad is lunch. Chilled Muscadet or dry cider are the obvious drinks. For more on how the different Bordier flavours behave once heat is involved, our guide to Bordier butter is the place to start.
Where to buy Bordier Seaweed Butter in the US
The French Pantry ships Bordier butter across the United States in insulated overnight packaging, straight from the workshop in Brittany.
- Churned Seaweed Butter by Bordier (4.4 oz): hand-churned Breton butter with iodised seaweed, the original Bordier flavoured butter and the reason this loaf tastes of the coast.
To see the rest of the range, browse the Maison Bordier collection.
Frequently asked questions
How much Bordier Seaweed Butter do I need for this recipe?
The loaf takes 80 g. A Bordier block is 125 g (4.4 oz), so one block covers it with about a third left over.
Can I substitute another butter?
Yes, though the loaf changes character. Bordier Buckwheat Butter doubles down on the Breton side and is excellent here. Salted Butter works too, but the trout then has to carry the savoury weight alone.
Can I use smoked salmon instead of trout?
Smoked salmon behaves the same way in the batter. Beechwood-smoked trout is milder and less oily, which is why Bordier chose it, but the substitution is straightforward.
How do I store the butter once it is open?
Keep it wrapped in its paper in an airtight box in the coldest part of the fridge and use it within about two weeks. It absorbs other flavours quickly. It freezes for up to three months.
Does Bordier butter need refrigeration?
Yes. Bordier butter is a fresh, hand-churned product and ships cold in insulated overnight packaging. Get it into the fridge as soon as the box is open.
How long does the loaf keep?
Wrapped, three days in the fridge. It is arguably better on day two, once the smoke and the seaweed have settled into the crumb. Bring it back to room temperature before serving.
Related reading
- Bordier Butter: What It Is, Why Chefs Love It, and How to Use It
- Paysan Breton: The Breton Butter Guide
- How to Choose Your French Butter: A Buyer's Guide
Recipe and photograph adapted from Maison Bordier, with thanks. The French Pantry is an authorized US retailer of Bordier butter.