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.
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 recipe, 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.
- cut strawberries into small pieces and put them in a small pan together with lemon juice and 30g (3 TBSP) icing sugar; simmer on medium/high heat for about 5 minutes, then turn off heat and add chopped basil leaves.
- mix gelatine with cold water and leave it to bloom for a minute, then manually whisk it into the hot berry compote.
- 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.
- whip cream to stiff peaks, then softened mascarpone; whip again to stiff peaks, cover bowl with cling film and refrigerate.
- once the strawberry gel is set, 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.
- with an electric whisk (or in a food processor) 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.
- 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 flour and turmeric – you want a light, airy mix.
- line a baking tray 28cm x 35cm (U.S. option HERE) with non-stick parchment paper; pour sponge mix over it and spread it out to even height; bake for 13 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 and flip everything once again – you want the top-baked side facing up.
- leave it to cool down with the paper on top and covered with a clean dish cloth.
- 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.