Viennese Whirls with Raspberry and Buttercream

Viennese whirls are the biscuit that taught me the difference between a recipe that works and a recipe that works every time. Get them right and they are astonishing: piped rosettes so tender they collapse into buttery sand the moment they hit your tongue, sandwiched with jam and cream. Get the paste too stiff and you cannot pipe them; too soft and they spread into puddles. The classic filling is vanilla buttercream and raspberry jam, and my one change is to fold ground freeze-dried raspberries through the buttercream, which turns it a real dusty pink and gives it the sharp, concentrated fruit flavour that ordinary raspberry buttercream, made with jam or essence, never quite manages.

Viennese in name, British in fact

The first thing to say about Viennese whirls is that they are not especially Viennese. They are a British biscuit that borrowed the glamour of the Austrian capital, in the same era and the same spirit that gave us Vienna bread and the Battenberg’s continental airs. The technique they lean on is genuinely Austro-Hungarian: a soft, pipeable butter dough in the tradition of Spritzgebäck, the piped butter biscuits of German and Austrian Christmas baking, whose name comes from spritzen, to squirt or pipe. British bakers of the mid-twentieth century adopted the piping method, sandwiched the results with jam and buttercream in the manner of a custard cream, and dressed the whole thing up with a fashionable foreign name. Marks and Spencer sold them by the million and fixed them in the national memory.

What defines the biscuit is that melting, sandy shortness, and it comes from two decisions. The first is the very low sugar content: fifty grams of icing sugar to two hundred of butter is a fraction of what a normal biscuit carries, so there is little sugar to crisp up and set hard. The second is cornflour, which replaces a portion of the wheat flour and, having no gluten, keeps the crumb impossibly tender. The result is a biscuit with almost no chew or snap at all, one that yields the instant you bite it. That fragility is the whole point, and it is why a Viennese whirl feels like such a luxury next to a sturdy digestive.

Getting a paste you can actually pipe

The engineering challenge of Viennese whirls is the paste, which has to be soft enough to force through a star nozzle yet firm enough to hold its ridges through the oven. Three things make this reliable. First, the butter must be properly softened, at cool room temperature, so it creams to a genuinely pale, fluffy state; cold butter gives a stiff paste that will make your hands ache and may split the bag, while over-warm butter gives a slack one that spreads. Four to five full minutes of beating is not optional, because it is the air you whip in that lets the paste hold its shape.

Second, do not overwork the flour once it goes in. Beat just until smooth, then stop, because working the wheat flour develops gluten and toughens what should be the tenderest biscuit in the tin. Third, if your paste feels stiff, add a teaspoon of milk to loosen it rather than fighting it; if it feels slack, chill it for ten minutes before piping. A sturdy, thick-walled piping bag and a large open star nozzle are worth having, since a thin bag will burst under the pressure this paste demands. Pipe from the outside inwards in a flat spiral, keeping the nozzle close to the tray, and accept that your first two will be practice.

Why chill before baking

Piped and ready, the biscuits go into the fridge for fifteen minutes before they see the oven, and skipping this is the single most common reason whirls spread and lose their definition. Chilling firms the butter back up so the ridges set in the heat before the fat has a chance to melt and slump. A whirl that has spread into a flat disc still tastes good, but you lose the pretty piped rosette that is half the appeal. Bake them at a moderate 170C only until the edges are pale gold and the biscuits are set; the tops should stay pale, because these are a biscuit you dry out rather than brown. They will feel soft when they come out and firm up as they cool, so leave them on the tray for five minutes before you dare to move them, as they are extremely fragile while warm.

The twist: freeze-dried raspberry buttercream

Here is where the whirls become genuinely special. Standard raspberry buttercream is usually just vanilla buttercream stained pink with jam or a drop of flavouring, and it tastes mostly of sugar. Freeze-dried raspberries change the game entirely. They are whole raspberries with the water removed under vacuum, so all the acidity, colour and flavour are left behind in a light, crisp crumb that grinds to a vivid pink powder. Ten grams of that powder carries the punch of a whole punnet, without adding any moisture that would make the buttercream weep or slump.

The effect is a filling that is properly tart and fruity, a natural deep pink, and a genuine counterweight to the sweet biscuit. Grind the raspberries in a spice mill or bash them in a bag with a rolling pin, then beat the powder into a simple buttercream. I still add a teaspoon of actual raspberry jam alongside the cream in each sandwich, because the jam brings a glossy stickiness and a slightly different, jammier flavour that plays against the fresh tartness of the powder. The two fruit elements together are far more interesting than either alone. This same trick lifts the buttercream in my melting moments with custard buttercream, and the raspberry-and-cream logic runs right through my pavlova with passionfruit and cream.

What can go wrong

If your whirls spread flat, the culprit is almost always warm butter or a skipped chill; soften the butter less next time and chill the piped biscuits properly. If the paste is impossible to pipe, it is too cold or too stiff, so let it warm for a few minutes or slacken it with a teaspoon of milk. If the biscuits crumble to pieces as you sandwich them, they are actually perfect and you are just handling them too roughly, so support each one flat on your palm. And if the buttercream is too soft to hold, it has been over-beaten or the kitchen is warm, so chill it for ten minutes to bring it back to a pipeable firmness.

Make it yours

The whirl is a frame you can hang almost any flavour on. Grind a spoon of freeze-dried strawberries or blackcurrants instead of raspberries for a different fruit, or leave the buttercream plain vanilla and dip the finished sandwich half in melted dark chocolate for a smarter, glossier finish. For a citrus version, beat the finely grated zest of a lemon into the biscuit paste and fill with lemon curd in place of the jam, which gives a sharper, brighter biscuit that cuts the butter cleanly. A scrape of coffee extract in the buttercream turns them into a grown-up petit four for the end of a dinner. Whatever you change, keep the cornflour and the low sugar in the biscuit, because that is the part doing the melting.

Storage and getting ahead

Unfilled, the baked biscuits keep in an airtight tin for up to five days and stay perfectly crisp-tender. Once sandwiched with buttercream and jam, though, they soften as they sit, because moisture from the filling migrates into the biscuit; they are best eaten within two days, and after that they turn from meltingly short to merely soft. For a party, the smart move is to bake the biscuits ahead, store them unfilled, and sandwich them a few hours before serving so the biscuit still has some structure. The paste itself does not freeze well once piped, though the buttercream keeps in the fridge for a week and freezes for a month, so you can get the fiddly fruit powder work done well in advance and assemble at leisure.