Hot chocolate with oat, soy, almond or coconut milk

FAT. Whole milk is around 3.5% fat, and that fat is what carries aroma compounds to the receptors and gives the drink body. Most plain plant milks are well below it — almond frequently around 1%, oat around 1.5% unless enriched. Less fat means a thinner drink and, more importantly, less flavour delivery: the chocolate is not weaker, it arrives less efficiently.

PROTEIN. Milk protein does two jobs in a hot chocolate: it stabilises the emulsion of cocoa butter in liquid, and it contributes to mouthfeel. Soy is the only common plant milk with a comparable protein content; oat and almond have very little, and rice has almost none.

SUGARS. Lactose is mildly sweet and it is always there. Oat milk is sweeter than dairy because the enzymatic process that makes it converts oat starch into maltose; almond and unsweetened soy are not sweet at all. A hot chocolate recipe balanced for dairy will taste under-sweet made with almond and slightly over-sweet made with oat.

WHAT PLANT MILKS ADD that dairy does not is stabilisers and emulsifiers — gellan gum, dipotassium phosphate, sunflower lecithin, added oils. Those are not padding; they are compensating for the three items above, which is exactly why the barista formulations behave so much better in a hot drink.

OAT is the best general-purpose choice and it is not close. It has body from its dissolved carbohydrate, it is naturally sweet, it foams well in the barista versions, and its own flavour is mild and cereal-like in a way that sits comfortably under cocoa. It also thickens perceptibly as it heats, which flatters a hot chocolate.

SOY is the technically best for emulsion stability because of its protein, and it makes a genuinely rich drink. Its own flavour is more assertive — beany to some palates — and dark chocolate covers it better than milk chocolate does. It is also the plant milk most likely to curdle, for reasons in the next section.

ALMOND is the thinnest and the least suitable without adjustment. Low fat, low protein, and its own flavour is delicate enough to disappear. It makes a watery hot chocolate unless you compensate with a richer chocolate, a higher dose, or a spoonful of nut butter — which is a good trick, because almond butter in almond milk restores the fat the milk is missing and reinforces the flavour that is already there.

COCONUT MILK — the drinking kind, not tinned — brings real fat and works well. Tinned coconut milk makes something closer to a dessert. Coconut fat is highly saturated, so the drink thickens markedly as it cools and can set to a soft cream in the bottom of a cup left standing. Its flavour is not neutral and the result is a coconut-and-chocolate drink rather than a hot chocolate.

CASHEW is creamy for its fat content and neutral in flavour, and is a good and expensive choice. RICE is sweet, extremely thin and the least suitable of the common options. PEA PROTEIN milks perform surprisingly well because they solve the protein problem directly.

Plant milks curdle in hot drinks for a different reason than dairy does, and the difference tells you what to do about it.

PLANT PROTEINS ARE SUSPENDED, NOT DISSOLVED, and the suspension is held by pH and by added stabilisers. Drop the pH — with something acidic — or raise the temperature sharply, and the proteins aggregate and drop out as visible flecks. Soy is the most susceptible because it has the most protein to aggregate.

THE TRIGGERS, in order of how often they are the culprit: heat shock, from pouring cold plant milk into a very hot base or overheating it directly; acidity, from coffee in a mocha, from citrus juice, or from a strongly acidic natural cocoa; and age, because a carton near the end of its life has drifted in pH already.

THE FIXES are all about avoiding shock. Heat the plant milk gently and separately rather than pouring it onto something near boiling. Warm it BEFORE combining with anything acidic. Use a barista formulation, which is specifically buffered against this. And if you are making a mocha, add the plant milk to the espresso rather than the espresso to the plant milk — the smaller volume meeting the larger tempers the change.

Two adjustments make plant-milk hot chocolate consistently better, and both follow from the fat and protein deficit.

USE MORE CHOCOLATE, NOT MORE COCOA. Chocolate brings cocoa butter, which replaces some of the fat the milk is not supplying. A plant-milk drink at 25g of chopped chocolate per 100ml is roughly as satisfying as a dairy drink at 20g. Cocoa powder in a low-fat plant milk gives the thinnest possible version of an already thin drink.

CHECK THAT THE CHOCOLATE IS DAIRY-FREE, which a great deal of dark chocolate is not — plenty of dark chocolate is made on shared equipment and carries a may-contain declaration, and some contains milk fat deliberately. The catalogue has a page on the difference between vegan and dairy-free, which is a real distinction rather than a pedantic one.

AND CONSIDER WATER. A drinking chocolate made with water and a good bar has no dairy problem to solve, tastes emphatically of chocolate, and is what a great deal of the traditional drinking-chocolate world has always done. It is the most underrated answer to this question.