Why sugar-free baking has finally come of age

Ask anyone who has tried to cut sugar from their baking and they will tell you the same story: dry sponges, bitter aftertastes and a crumb that collapses the moment you look at it. It is no wonder so many people quietly give up. But sugar-free baking has come a long way, and the trick is not to fight the absence of sugar — it is to choose recipes that never leant on it heavily in the first place. A lemon polenta cake is the perfect example. It is naturally rich from ground almonds, has a soft, faintly grainy crumb from fine polenta, and relies on citrus zest for the sort of bright, insistent flavour that makes you forget you were ever counting the sweet stuff.

This version is gluten-free as well, which makes it a genuinely useful cake to have in your repertoire — whether you are baking for a coeliac relative, a household cutting back on refined sugar, or simply yourself on a wet Tuesday afternoon.

Choosing a natural sweetener that actually tastes good

Not all sugar replacements behave the same way in a cake, and the one you pick will change your results more than any other ingredient. Here is what to expect from the main options on UK supermarket shelves.

• Erythritol — roughly 70% as sweet as sugar, with a slightly cool sensation on the tongue. It works beautifully in dense, moist cakes like this one, but browns far less, so expect a paler top than you might be used to.
• Xylitol — closer to sugar in both sweetness and browning, which makes it a good all-rounder. Do keep it well away from dogs, as even small amounts are seriously toxic to them.
• Stevia blends — intensely sweet, so you need very little, and they can turn bitter if overdone. Blends bulked out with erythritol are far easier to bake with than pure stevia.
• Monk fruit — the most neutral in flavour, with no cooling aftertaste, but it is the priciest of the bunch.

For this recipe, a granulated erythritol-and-stevia blend sold specifically for baking is the simplest route. It measures roughly like sugar, which means you are not constantly converting quantities in your head.

What the almonds and polenta bring to the table

Ground almonds are doing a lot of quiet work here. They bring fat, which keeps the crumb tender, and moisture, which is exactly what sugar-free bakes usually lack. They also add a gentle nuttiness that sits nicely alongside lemon. Use whole blanched almonds blitzed in a food processor if you can — the freshly ground ones are noticeably oilier and give a better texture than the bagged stuff.

Polenta is the other half of the partnership. It gives the cake structure without the heaviness of wheat flour, and that characteristic sandy grain that soaks up lemon syrup beautifully. Choose a fine polenta or fine cornmeal. Coarse polenta will leave you chewing, and quick-cook varieties can turn gluey.

The recipe: zesty gluten-free sugar-free lemon polenta cake

This makes one 20cm round cake, serving eight to ten. You will need a deep springform tin lined with greaseproof paper on the base and sides.

• 200g unsalted butter, softened, or 180ml mild olive oil
• 150g granulated baking sweetener
• 4 large eggs, at room temperature
• 200g ground almonds
• 100g fine polenta or fine cornmeal
• 1½ tsp gluten-free baking powder
• ½ tsp fine sea salt
• Zest of 3 unwaxed lemons, finely grated
• 60ml fresh lemon juice
• 1 tsp vanilla extract
• 1 tbsp natural yogurt or soured cream

Heat the oven to 170°C fan, 190°C conventional, gas mark 5. Beat the butter and sweetener together for a full four minutes until pale and fluffy — longer than you would with caster sugar, because the granules do not dissolve in the same way. Add the eggs one at a time, beating well between each. Fold in the ground almonds, polenta, baking powder, salt and lemon zest until just combined, then stir through the lemon juice, vanilla and yogurt. The batter will be looser than a standard sponge.

Pour into the prepared tin, level the top and bake for 45 to 50 minutes, until deep golden and a skewer inserted in the centre comes out with a few moist crumbs clinging to it. Cool in the tin for fifteen minutes before releasing the sides and moving to a rack.

For a glossy finish, warm three tablespoons of lemon juice with two tablespoons of sweetener and spoon it over the cake while it is still warm. It sinks in and keeps everything beautifully damp.

Baking notes and troubleshooting

• Do not judge by colour alone. Sugar-free cakes brown reluctantly, so test with a skewer and press the centre — it should spring back.
• Tent it early. If the top is catching at the 35-minute mark, lay a sheet of foil loosely over the tin.
• Stop mixing once the almonds go in. Overworking the batter releases oil from the nuts and can make the cake greasy.
• Give it a night. This cake genuinely improves after twelve hours in an airtight tin, as the polenta softens and the lemon settles.

Serving, storing and easy variations

Serve in generous wedges with thick Greek yogurt, crème fraîche or a spoonful of lightly crushed raspberries. It keeps for four days in an airtight tin at room temperature and freezes well for up to three months, wrapped tightly and defrosted overnight.

Once you have the base recipe down, it is very forgiving. Swap the lemon for orange zest with a sprig of finely chopped rosemary, or go lime and toasted coconut. A handful of raspberries scattered over the batter before baking adds pockets of sharpness without upsetting the sugar-free maths. Bake it once and it will quietly become the cake you make when someone says they cannot eat gluten or sugar — and nobody at the table will feel they are missing out.