Replacing the butter with olive oil when baking

Olive oil baking is not a health compromise — it is a Mediterranean tradition older than butter cakes. But you cannot simply pour oil where the recipe says butter. Here is what actually changes, and how to get it right.

There is nothing novel about baking with olive oil. Southern Italy, Greece, Spain and Provence have been doing it for centuries — a great many traditional Mediterranean cakes, biscuits and breads are oil-based, not because anyone was counting saturated fat but because oil was what the household had. Butter was a northern ingredient, and in olive country it was scarce and expensive.

Which is a useful way to approach the swap. You are not degrading a butter recipe; you are moving it into a different and equally old tradition. Do that thoughtfully and the results can be better than the original. Do it carelessly and you get a greasy, flat cake that tastes faintly of salad.

Butter in recipe	Olive oil to use	Note
100 g butter	75 ml olive oil	The reliable three-quarters rule
1 cup butter	3/4 cup olive oil	Same ratio, cup measures
50 g butter	40 ml olive oil	Round down rather than up
Butter for greasing tins	Olive oil, brushed thin	Works well; flour the tin after
Butter in laminated pastry	Do not substitute	Layers need solid fat
Butter in shortbread	Do not substitute	The whole texture is butter

Why the ratio is three-quarters

Butter is not pure fat. It contains roughly 15 to 20 per cent water plus milk solids, whereas olive oil is essentially all fat. Pour oil in at a one-to-one volume and you have added markedly more fat and removed the liquid, which gives a heavy, greasy crumb.

Using around three parts oil to four parts butter restores the fat balance. If a bake comes out slightly dry, add a spoonful of milk, yoghurt or water to replace the missing moisture rather than adding more oil — that is the correction people get wrong most often.

What changes in the finished bake

Three real differences, none of them subtle.

Texture. Butter cakes are made by creaming butter with sugar, whipping air into a solid fat. You cannot cream a liquid, so oil cakes rise less from that mechanism and lean on eggs and chemical raising instead. The result is a finer, denser, more even crumb — less fluffy, more tender.

Keeping. This is the genuine advantage. Because olive oil stays liquid at room temperature while butter sets hard, oil cakes stay moist for days where a butter cake goes stale and firm overnight. A good olive oil loaf is often better on day two.

Flavour. Olive oil is not neutral. That can be glorious or ruinous depending on the bake and the oil you choose.

Best bakes for olive oil	Citrus cakes, almond cakes, chocolate cakes, muffins, brownies, focaccia, biscotti, banana bread
Poor bakes for olive oil	Puff and flaky pastry, shortbread, croissants, butter icing, sugar cookies
Ratio	3 parts oil to 4 parts butter, by volume
Method change	No creaming stage — whisk oil into sugar and eggs
Oil to use, delicate bakes	Mild, ripe, low-bitterness oil
Oil to use, robust bakes	Fruity or peppery oil, with chocolate, citrus or herbs
Storage of the bake	Keeps moist notably longer than butter equivalents

Choosing the oil — the part everyone gets wrong

Do not reach for your fiercest, greenest, most peppery bottle. In a delicate sponge, a bitter oil is aggressive and the pepper reads as a fault. Save the good early-harvest oil for drizzling over the finished cake, which is a genuinely wonderful thing to do with a plain almond or citrus cake.

For baking, use a mild, ripe, low-bitterness extra virgin. It should still taste of something — please do not use so-called light olive oil, which is refined and lightly flavoured, not lower in calories, a piece of labelling that misleads more shoppers than almost any other in the category. Where a robust oil genuinely earns its place is with strong partners: dark chocolate, orange zest, rosemary, fennel seed, almonds. Chocolate and a peppery oil is a famously good pairing.

Method matters too. Since there is no creaming, whisk the sugar and eggs together first until pale and thickened, then pour the oil in slowly while whisking. That builds what structure you can before the fat arrives. Fold in the dry ingredients gently at the end.

The health question, briefly and honestly

Olive oil is predominantly monounsaturated fat and butter is predominantly saturated, and dietary guidance broadly favours replacing saturated fat with unsaturated. That is a fair reason to prefer olive oil in baking. But keep perspective: a cake made with olive oil is still a cake, with the same sugar and flour it always had, and the swap does not turn it into health food. This is general information, not medical advice.

One technical footnote worth knowing. Baking temperatures are gentler on oil than frying, and the oil is dispersed through a wet batter rather than sitting in a hot pan, so a good extra virgin handles baking perfectly well. Its most delicate aromatics will fade in the oven, which is another reason not to sacrifice an expensive bottle for the job.

Practical takeaways

• Use three parts oil to four parts butter, by volume, and adjust liquid rather than fat if the bake is dry.
• Skip the creaming stage — whisk eggs and sugar first, then stream in the oil.
• Mild oil for delicate bakes, fruitier oil for chocolate, citrus and herbs.
• Never substitute in pastry or shortbread, where solid fat is doing structural work.
• Expect a moister cake that keeps longer — often better on the second day.

Baking with olive oil: common questions

How much olive oil replaces butter in baking?

Roughly three parts oil to four parts butter by volume — so 75 ml of oil for 100 g of butter. Butter contains water and milk solids, so a one-to-one swap adds too much fat.

Will my cake taste of olive oil?

Somewhat, and that is often the point. Use a mild ripe oil for delicate bakes; with chocolate, citrus, almond or rosemary a fruitier oil is a real asset.

Can I use olive oil in pastry or shortbread?

No. Puff pastry, croissants and shortbread depend on solid fat for their layers and texture. Oil cannot do that job.

Does olive oil make cakes last longer?

Yes. Because it stays liquid at room temperature, olive oil cakes stay moist for several days, while butter cakes firm up and stale more quickly.

Should I use extra virgin or light olive oil for baking?

Extra virgin, but a mild one. Light olive oil is refined and lightly flavoured — the name refers to flavour and colour, not calories.

General culinary background on fat substitution in baking and Mediterranean oil-based baking traditions.