Keto Strawberry Mousse Swiss Roll. Nut-FREE. Light as a feather. Beautiful. Superb taste. And just a little over 2g net carbs per slice.
A real pièce de résistance.
This keto Swiss Roll is simply perfect in every sense. Not sickly sweet. Melt-in-the-mouth. Refreshing flavour. It could be on sale in a high-end French patisserie and it would be indiscernible from any sugar-loaded creation. It took a long time to get right. But the effort and persistence was worth it and I’m ultra proud of my newest low-carb showpiece.
Thinking it might be too complicated for you to have a go? Absolutely not! It’s actually pretty easy, considering the stunning result. All you have to do to re-create this gem is to to follow my recipe to the letter. In the same order. With the same ingredients (except where I’ve indicated possible subs or omissions – read on…). And using metric weighing scales (this is non-negotiable – cups/spoons/ounces conversions will pretty much ensure a FAIL).
How To Make Keto Strawberry Mousse Swiss Roll
There are 4 easy parts to complete. The first is making the strawberry gel, as it needs to cool down properly in order to set. Secondly, you whip the creamy filling and combine it with the strawberry gel to obtain a mousse. Thirdly, you bake the sponge. The fourth and final part is spreading the mousse filling over the sponge and rolling it into a Swiss Roll.
Then it’s about having the willpower to wait for it all to set nicely. I think 2 hours is the absolute minimum. But if you leave it overnight, flavours will intensify, it will set well enough to slice effortlessly and it will taste 100% better.
As for ingredients, variations that will ensure success are as follows:
Basil leaves – Omit if you wish, although I personally feel that the strawberry gel tastes better with than without. If you do use them, they must be fresh – not dried or frozen.
Mascarpone – Replace with double (heavy) cream if it’s something you really can’t find.
Turmeric powder – Entirely OPTIONAL, as I only use it to give the sponge a more intense yellow colour.
MCT oil – You can swap it for any oil you like, but it must be MILD in flavour. Extra virgin olive oil and coconut oil would NOT be suitable (too heavy).
Strawberries – You can pretty much use any berries you like.
That’s it! You cannot replace the lupin flour. It’s very low carb and quite neutral but ‘earthy’ in flavour. Lupin flour is very light and totally different, both in texture and ‘behaviour’, from coconut flour or almond flour – which have a much higher fat content and therefore create ‘heavy’ bakes. If you have a peanut or legume allergy/intollerance/aversion, you should avoid lupin seeds – in which case, you’ll need to skip this recipe. Or experiment with other flours knowing that the sponge will not have the right consistency/might stick/may break whilst rolling/etc..
Same goes for tapioca flour. I’m fully aware that it’s a starch. And yes, I know that it is very high carb and therefore not keto-friendly in high amounts. BUT. You only need 10g. That’s for the entire cake. Once you’ve cut 12 slices, each serving contains less than 1g carbs from the tapioca. Surely anyone can see that it’s fine, right? Great. Please refrain from posting vacuous comments saying ‘tapioca is not keto’. Ketosis is a metabolic state that you achieve with extreme carb restriction. End of. It’s not about food lists. If you eat ‘clean’ keto – as I do – tapioca (in minimal amounts) is a wholesome choice you should NOT be afraid of.
Also, I use pure erythritol and pure stevia because together they create the right ‘bulk’ and ‘consistency’. There will be zero aftertaste as long as you use the pure products that I have provided links for. If you use different brands, or change them for completely different sweeteners, I cannot guarantee the same result.
Right then. Here we go. It’s a long read, but I wanted to be as precise and clear as possible, so that YOU can mirror what I did and create your own magnus opus.
Enjoy!
Keto Strawberry Mousse Swiss Roll
Ingredients
Filling:
- 150 g fresh strawberries - net weight
- 1 tsp beef gelatine powder (U.S. option HERE)
- 1.5 TBSP cold water
- ½ lemon - juice only
- a handful of fresh basil leaves - chopped
- 75 g mascarpone
- 75 g whipping cream
- 50 g icing sweetener (U.S. option HERE)
Sponge:
- 4 eggs - separated
- 70 g erythritol (U.S. option HERE)
- ½ tsp pure stevia powder (U.S. option HERE)
- ½ lemon - grated zest only
- 50 g MCT oil (U.S. option HERE)
- 30 g lupin flour (U.S. option HERE)
- 10 g tapioca starch (U.S. option HERE)
- ½ tsp turmeric powder optional - for colour
Instructions
To make the Strawberry Mousse filling:
- cut strawberries into small pieces and put them in a small pan together with lemon juice and 30g (3 TBSP) icing sweetener; simmer on medium/high heat for about 5 minutes, then turn off heat and add chopped basil leaves.150 g fresh strawberries, ½ lemon, 50 g icing sweetener, a handful of fresh basil leaves
- mix gelatine with cold water and leave it to bloom for a minute, then manually whisk it into the hot berry compote.1 tsp beef gelatine powder, 1.5 TBSP cold water
- pour the mixture into a tall beaker and blitz using an immersion (stick) blender, with up/down motion until frothy, airy and smooth; leave aside to cool down completely, then transfer to the fridge while you continue with the recipe.
- beat mascarpone and 20g (2 TBSP) icing 'sugar' with a fork to soften it.75 g mascarpone
- whip cream to stiff peaks, then add the softened mascarpone; whip again to stiff peaks, cover bowl with cling film and refrigerate.75 g whipping cream
- once the strawberry gel is cold and firmer, loosen it with a fork, then gently combine it it with the whipped mascarpone cream to achieve a mousse-like consistency; keep chilled while you proceed with the sponge.
To make the Sponge:
- with your stick whisk whip egg whites to soft peaks, then add sweeteners bit by bit as you continue to whip to a stiff and glossy meringue-like consistency.4 eggs, 70 g erythritol, ½ tsp pure stevia powder
- pre-heat oven to
170 °C static. - using a manual baloon whisk, and working gently to avoid deflation, incorporate lemon zest, then egg yolks one-by-one, then oil, and sifted lupin flour, tapioca starch and turmeric - you want a light, airy mix.½ lemon, 50 g MCT oil, 30 g lupin flour, ½ tsp turmeric powder, 10 g tapioca starch
- line a 28 x 35 cm baking tray with non-stick parchment paper; pour sponge mix over it and spread it out to even height; bake for 15 minutes, then remove from oven and let cool in situ for a couple of minutes.
- place a new sheet of parchment paper over the sponge and hold it as you flip the whole thing over your worktop.
- gently peel away the old parchment sheet, replace it with a fresh sheet, cover with a clean dish cloth, and leave it to cool down.
To assemble:
- when the sponge reaches room temperature, spread the strawberry mousse all over (2cm inwards from all edges) and roll the long side - use the parchment paper to help lift and roll, and re-centre the sponge as you roll, so as to stay in the middle of the paper.
- make sure the end seam is facing down, wrap the roll tightly, then wrap it again in aluminium foil.
- refrigerate for at least 2 hours - best left overnight for the flavours to infuse and the swiss roll to compact nicely.
- (optional) when ready to serve, sprinkle with sifted icing sugar before slicing.
Notes
Nutrition
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Y
Made it again today. Still one of my favourites.
Light as a feather and absolutely delicious.
The strawberry & basil mix is genius. I know it’s weird to describe a food as elegant, but this is what truly fits the description here. It is the kind of recipe that makes me not miss store bought processed garbage because none will be close. Thank you for amazing recipes!
Thank you Mari. I’m truly humbled by your comments and hope you will continue to enjoy my recipes. x
I made this yesterday and it’s delicious. The combination of strawberry with basil is just brilliant. Wonderful dessert. This and the Italian Milk Pie will surely be on my frequent rotation. Thank you!
Hey Mari, that’s lovely. It would be great if you could add your star rating. Thank you.
Can you use Almond flour instead of Lupin Flour? would it be the same amount?
As long as it’s fine almond flour it will be OK. You would probably need to use a greater quantity, because lupin is more absorbent.
that looks awesome! I don’t think I can roll so nicely 😀 Maybe I can make it in a cake pan and frost the top …
Hello Kay. You could cut the sponge into squares and layer the strawberry mousse, like a tiramisù. 😀
Do you have a lupin flour recommendation that does not have rice flour in it? I am grain free.
Hi Mary, lupin is the seed of a leguminous plant. Lupin flour is grain-free and should not contain rice or other fillers. It is pretty much guaranteed to be organic, non-GMO and unadulterated. I have updated the links provided in the recipe, ensuring they point to only natural products.For the U.S. Lupina seems to be the best- HERE‘s the link.