No-bake desserts: gelatine, agar, panna cotta and mousses that hold their shape

Gelatine comes in two forms. Sheets are easier: they're simpler to measure (a silver-grade sheet weighs about 2 g) and don't form lumps. Powder is cheaper and more widely available.

Any gelatine is soaked in cold water first. Powder in 5–6 parts water (10 g in 50–60 ml) for 10 minutes — it absorbs all the water and swells. Sheets in a bowl of plenty of iced water for 5–10 minutes, then squeezed out. Dissolve the bloomed gelatine in warm, not boiling, liquid.

The dose depends on the result you want: a wobbly panna cotta or a jelly you can cut with a knife. Amounts are per 1 litre of liquid.

Fresh pineapple, kiwi, papaya, mango, fig, melon and ginger contain enzymes that break down the protein in gelatine. Jelly with them won't set at all, however much gelatine you use.

The fix: bring these fruits to the boil for 1–2 minutes — the enzymes are destroyed. Or use canned fruit, which has already been heated. Or swap gelatine for agar — it's plant-based and the enzymes don't affect it.

Agar is made from seaweed. It's 8–10 times stronger than gelatine and, unlike gelatine, must be boiled: it only dissolves after 1–2 minutes at a boil.

Agar sets at 35–40 °C, right on the counter, in 20–30 minutes. The jelly is firmer and slightly brittle rather than wobbly. On the plus side, it doesn't melt at room temperature.

The classic Italian dessert: cream, sugar, vanilla and just enough gelatine that it barely holds its shape and melts in the mouth.

Whipping needs cream of 33–35% fat. 20% cream won't whip. Everything must be cold: cream, bowl and whisks — put them in the freezer for 10 minutes.

Whip on medium speed to soft peaks, then add icing sugar (30–40 g per 250 ml) and whip to firm peaks. Stop in time: overwhip and the cream turns into butter and whey.

A mousse is a flavoured base with whipped cream or egg whites folded in. The main rule: fold the light into the heavy gently, with a spatula, in bottom-to-top strokes to keep the air.

Egg-free chocolate mousse: melt 150 g dark chocolate and cool it to 35–40 °C (warm, not hot). Whip 300 ml 33% cream to soft peaks. Fold a third of the cream into the chocolate first to loosen it, then the rest. Spoon into glasses and chill for 3 hours.

Berry mousse: 300 g berry purée, 60–80 g sugar, 10 g gelatine, 300 ml whipped cream. Dissolve the gelatine in the warm purée, cool until it starts to thicken and fold in the cream.

A base for no-bake cheesecake, tarts and slices: 200 g shortbread or digestive biscuits crushed to crumbs and 80–100 g melted butter. The mixture should hold together when squeezed in your fist.

Press the crumbs firmly into the tin with the base of a glass and chill for 30 minutes until the butter sets. For crunch, add 1 tbsp cocoa, a handful of ground nuts, or swap some of the biscuits for wafers.

Gelatine desserts need at least 4 hours in the fridge, ideally overnight. Don't put them in the freezer to speed things up: the gelatine crystallises and the dessert turns watery once thawed.

To turn a dessert out, dip the mould in hot water for 5–10 seconds, run a thin knife round the edge, cover with a plate and invert. If it won't come, another 5 seconds in hot water. Silicone moulds simply peel away.

Make layered jellies in stages: pour each new layer once the previous one has set but is still tacky to the touch, and the new layer has cooled to room temperature. Otherwise the layers blend.