French Walnut Coffee Cake (Gâteau Grenoblois)

Known in France as Gâteau Grenoblois, this French Walnut Coffee Cake is a specialty from Grenoble, in South Eastern France, where walnuts are plentiful. It features a fluffy crumb made with ground walnuts and is flavored with brewed coffee, all under a simple icing.

This cake is naturally gluten-free and dairy-free, but delivers the same richness as any rustic French cake. 

If you love French regional cakes, add this one to your list! A favorite of French home bakers in the Fall, this cake recipe relies on walnuts to create a rich-tasting, yet fairly light cake.

Along with good-quality walnuts, it includes staple ingredients such as eggs, sugar, brewed coffee and cornstarch – which you likely already have on hand. I love its simplicity, yet it delivers a satisfying texture and rich flavor thanks to the walnuts. 

Unlike American or British walnut cakes – which are often covered with frosting – this French version is simply finished off with an icing of sugar and coffee. This makes it a considerably lighter version, well suited for an afternoon snack. 

Since this cake recipe includes no flour, nor butter (a rare occurrence in France cakes!), it is also gluten-free and dairy-free. 

About « Noix de Grenoble » 

Traditionally used in this recipe, Noix de Grenoble (translating to Grenoble walnuts) are harvested in the Auvergne-Rhone-Alpes region of France. It is said the local alpine climate, with cold winters, naturally protects the fruits and provides fresh water, producing the highest quality walnuts. Grenoble walnuts are prized for their incomparable flavor and tender texture, leading to them being commonly used all throughout France.

In 1938, the AOC (controlled term of origin) was given to the Grenoble walnut, later replaced in 1996 by an AOP (protected designation of origin). This labels certifies the walnuts are produced within a strict geographical area limited to only select French departments along the Alpine Isère Region Valley and held to high-quality standards (size, irrigation, harvesting, etc.). 

The local cooking repertoire is naturally walnut-centric, with the Gâteau Grenoblois being perhaps the most famous specialty, along with the walnut caramel tart – a recipe you can find in my cookbook: Rustic French Cooking Made Easy.

Shopping for Walnuts

Outside of France, Noix de Grenoble are harder to find, but a few specialty stores sell them. So if you do spot them, make sure to grab some. They will likely be pricier than other walnuts, but worth the splurge. 

However, if you opt for “regular” walnuts (often referred to as English), I assure you this cake will still taste delicious! 

You can buy whole nuts or shelled nuts (more convenient); although do know the latter tend to go rancid quicker. Whole nuts can be kept up to 6 months at room temperature. Shelled nuts should be kept in the fridge and will last up to 3 months. 

How to grind the walnuts? 

For grinding the walnuts, or nuts in general, a food processor is recommended. Place the walnuts in the processor and pulse, 2 seconds at the time, until they are evenly ground. Stop when the walnuts are just ground enough and do not use the process button (only pulse). A long process time will make the mixture oily. 

Cooking Tips & Substitutions :  

• Use pristine equipment. When beating the egg whites, make sure you are using a bowl and beater that are perfectly clean. Egg whites tend to refuse to whip if they encounter any residual fat or even if there are tiny amounts of egg yolk.
• Fold, don’t stir. When folding the egg whites with the walnut mixture, use a large rubber spatula and be gentle. The important thing is not to stir, but fold. In small additions, carefully place a portion of the egg whites on top of the walnut mixture and fold it in by using a flipping motion. Stop when the batter is just uniform – do not overmix. 
• For a healthier version of this cake, you can skip the icing. Also do know the icing helps preserve the cake longer. With no icing, enjoy the cake within 2 days. 

How to store this French Walnut Coffee Cake

• Chill it. After making (and enjoying) this cake – if you have any leftovers – you can cover it with plastic film and store it in the fridge for up to 4 days.
• Don’t freeze it. I don’t recommend freezing this cake. The texture is delicate, and the cake will likely get soggy/mushy when thawing. 

I hope you’ll love this French Walnut Coffee Cake (Gâteau Grenoblois) as much as I do! If you have any questions, please leave a comment. 

More French cake recipes you may like: 

• Classic French Apple Cake
• Chestnut Cream Cake (Gâteau Ardéchois)
• Lemon Yogurt Poppy seed Cake
• Classic French Chocolate Moelleux Cake
• Classic French Pear Cake

French Walnut Coffee Cake

Print Recipe

Serves: 6-8 Prep Time: 20 Minutes Cooking Time: 45 Minutes 45 Minutes

Nutrition facts: 200 calories 20 grams fat

Rating: 4.5/5

( 4 voted )

Ingredients

2 1/2 cups (250g) whole walnuts
5 medium eggs, at room temperature
1 cup (200g) sugar
2 tbsp (30ml) strong brewed coffee
2/3 cup (100g) cornstarch
For the icing:
1 1/2 cup (150g) icing sugar
2-4 tbsp (30-60ml) strong brewed coffee
Extra whole walnuts, for decorating

Instructions

Step 1 – Grind the walnuts and set aside. Make sure to keep 6-8 whole walnuts for decorating the cake.

Preheat your oven to 340°F (170°C) with a rack in the middle. Grease a 8” or 9” circular pan with butter (or dairy-free alternative) and line the bottom with a circle of parchment paper. Set aside.

Step 2 - Separate the egg whites and yolks in two different large baking bowls. Add the sugar to the egg yolks and whisk until fluffy and lighter in color. Add the brewed coffee and whisk to combine. Add the cornstarch and whisk until incorporated.

Step 3 - Switch to a spatula, and incorporate the ground walnuts. The batter will be rather thick and sticky.

Step 4 – In a separate and clean bowl, whisk the egg whites to a stiff peak. With the spatula, fold 1 scoop of the egg whites into the walnut batter to loosen its texture. Then, add about ¼ or less of the egg whites and fold gently. Stop mixing when just incorporated. In three or four more additions, fold in the rest of the egg whites. The batter should be airy and “jiggly”.

Step 5 – Pour the batter into the prepared pan. Bake for 40-45 minutes, until the cake is puffy and the center is set. Transfer onto a cooling rack, let cool completely and remove from the pan.

Step 6 – Prepare the icing. In a small bowl, combine the icing sugar with 2 tablespoons (30ml) of brewed coffee. Mix until smooth. Add more coffee – 1 teaspoon at a time - to thin out the icing. The icing should reach a thick syrup consistency. Pour the icing onto the cake and smooth it out with a spatula or the back of the spoon.

Add whole walnuts atop for decoration. Let the icing set for 1 hour at room temperature before serving.