Strawberry rhubarb traybake only works if the rhubarb does not turn soggy. The solution: cut 1 cm slices across the grain and let the batter act as a barrier between the baking tray and the acidity of the fruit. Thinner slices turn mushy, thicker slices stay woody after 30 minutes.
We have been baking this cake every strawberry and rhubarb season for years. The combination of tart rhubarb, sweet strawberries and a creamy Mascarpone layer makes it the spring cake that guests always reach for first. The Thermomix® mixes the batter in 25 seconds, evenly and without any lumps of flour.
Strawberry Rhubarb Traybake with the Thermomix®
Ingredients 0 / 11 ✓
- 700 g rhubarb
- 400 g strawberries
- 400 g flour, type 405
- 1/2 sachet baking powder
- 250 g raw cane sugar (brown)
- 40 g vanilla sugar
- 300 g butter softened
- 1 pinch salt
- 4 eggs
- 250 g Mascarpone
- 3 egg yolks
Instructions 0 / 5
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1
Prepare the rhubarb and strawberries.
Wash the rhubarb, cut off the ends, peel the outer layer and slice across the grain into pieces about 1 cm thick. Wash the strawberries, remove the hulls and quarter them.
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2
Mix the batter.
Add the flour, baking powder, sugar, 10 g vanilla sugar, butter, salt and eggs to the mixing bowl and mix for 25 sec / speed 5.
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3
Spread the batter and preheat the oven.
Spread the batter evenly over a greased baking tray or one lined with baking paper, then rinse the mixing bowl. Preheat the oven to 170°C (top and bottom heat).
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4
Arrange the rhubarb and strawberries.
Spread the rhubarb and strawberries evenly over the batter base. Add the Mascarpone, egg yolks and remaining vanilla sugar to the mixing bowl and mix for 6 sec / speed 5. Spread the mixture evenly over the fruit layer.
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5
Bake the cake.
Bake the cake for 30 minutes in the middle of the oven.
Video
Nutrition per serving
Why the rhubarb needs to be 1 cm thick
Rhubarb contains a lot of oxalic acid and water. If you slice it too thin (under 8 mm), it releases so much liquid during baking that the Mascarpone layer cannot set and the cake turns wet. At 1 cm thick, cut across the grain, the structure stays stable and the rhubarb cooks through without falling apart.
The direction of the grain matters: slices cut along the grain stay fibrous and tough. Cut across the grain, the fibres break down and the rhubarb becomes tender. The outer skin must be removed because it turns leathery during baking and gives an unpleasant texture.
Sponge batter at speed 5, not kneading mode
The batter for this traybake is a classic sponge: soft butter, sugar, eggs and flour. 25 seconds at speed 5 is enough to bring all the ingredients together evenly without overworking the flour. Kneading mode would develop the gluten too much and the cake would turn dense instead of light.
The butter must be at room temperature (about 20°C) so it can combine with the sugar. Cold butter straight from the fridge cannot be worked in evenly and leaves lumps in the batter. The raw cane sugar gives the batter a light caramel note that complements the acidity of the rhubarb.
Batter as a liquid barrier
The sponge batter is spread evenly over the baking tray with a spoon and forms the first layer. This layer of batter prevents the acidity from the rhubarb and strawberries from reaching the tray directly and making the base soggy. Without this barrier, the cake would end up wet at the bottom and dry at the top.
Baking paper or greasing the tray only prevents sticking, not sogginess. The starch in the batter absorbs the liquid during baking and keeps the structure stable. That is why this cake works better than recipes where fruit sits directly on shortcrust pastry.
Mascarpone and egg yolk topping
The Mascarpone mixture of 250 g Mascarpone, 3 egg yolks and the remaining vanilla sugar is blended smooth in 6 seconds at speed 5. Too short and egg yolk streaks remain, too long and the mixture becomes too airy and collapses during baking. The egg yolks bind the Mascarpone and ensure the layer sets during baking without curdling.
The Mascarpone mixture is poured evenly over the rhubarb and strawberries and spreads itself during baking. It forms a creamy top layer that softens the sharpness of the fruit and gives the cake its characteristic look. Without the egg yolks, the Mascarpone would stay liquid and not set.
170°C top and bottom heat for 30 minutes
The cake is baked at 170°C top and bottom heat in the middle of the oven. At a higher temperature, the Mascarpone layer burns on top before the sponge is cooked through underneath. At a lower temperature, the cake does not set and stays wobbly in the centre.
Fan-assisted heat is not ideal for this cake because the circulating air dries out the surface too quickly and the Mascarpone cracks. Top and bottom heat bakes more evenly and gives the cake a smooth, creamy surface. After 30 minutes the cake is ready when the Mascarpone layer has set and looks lightly golden.
More rhubarb recipes
If you want to do more with rhubarb:
Goes well with: Vanilla ice cream and icing sugar.
Also worth trying: Fried Egg Cake with the Thermomix®.
- Strawberry Rhubarb Jam Thermomix®
- Strawberry Rhubarb Lemonade Thermomix®
- Rhubarb Mug Cake
- Rhubarb Vanilla Liqueur Thermomix®
- Strawberry Rhubarb Gin
