Gateau Breton is a traditional butter cake from the Brittany region in north western France. It is uncomplicated and requires just a few pantry staples to make, but like all traditional recipes, benefits from high quality ingredients.
This basic version is unfilled and it just perfect as it is – like a shortbread but a little softer and more cake-like – but it can also be made with a layer of plum or raspberry jam, or salted caramel in the middle.
Because, you know, you can’t have too much sugar or butter, right?!
The traditional recipe calls for semi-salted butter, but I couldn’t find any so I did a spot of googling… according to the butter manufacturer’s website I stumbled on, to substitute unsalted butter for salted you should add 1/4 teaspoon of fine salt for every 115g /half cup/stick/1/4lb of unsalted butter. But I wanted semi-salted butter, so I added 1/4 teaspoon to 250g (1 cup plus 2 Tbsp) butter and decided it was close enough. I’m satisfied with the very slight saltiness, which offsets the sugar and fat nicely, and I wouldn’t recommend normal salted butter for this recipe. But use semi-salted if you can find it.
Makes 1 x 24cm (9″) cake
24 pieces of varying sizes, if cut in the traditional diamond pattern
Preparation: 10 minutes
Baking: 35 – 40 minutes
Cooling: at least 2 hours
Keeps: a month in an airtight container in the pantry
6 large egg yolks
250g (1 1/4 cups) granulated sugar
360g (2 4/5 cups, spooned and scraped) all-purpose (plain) flour
1/4 tsp baking powder
250g (1 cup plus 2 Tbsp) semi-salted butter, softened
OR 250g (1 cup plus 2 Tbsp) unsalted butter plus 1/4 tsp fine salt
1 large egg yolk, lightly beaten, for glazing
Preheat oven to 170°C / 340°F / Gas Mark 4, and generously butter a 24cm (9″) springform cake pan.
In a large bowl or the bowl of a stand mixer, beat the egg yolks and sugar together until light and fluffy, about 3 minutes.
Whisk together the flour and baking powder (and salt, if using) and add to the egg yolk mixture. Add the softened butter and mix well to combine. The mixture will have the consistency of cookie dough.
Press the dough gently into the cake pan and smooth the top.
Brush generously with the lightly beaten egg yolk, then use a fork to mark the top in a cross-hatch pattern.
Bake in centre of oven for 35 – 40 minutes, until golden.
Remove from oven, remove the side of the cake pan and allow to cool completely on a wire rack.
Remove the base of the cake pan with a fine offset spatula and cut into diamonds – first, cut across into six, then cut on a 45° angle to those slices.