4 baker-approved swaps you can make in your recipes if you're missing key ingredients

• Buttermilk, vegetable oil, eggs, flour, and sugar are all key ingredients in many baking recipes.
• Claire Ptak, owner of the London bakery Violet, offered up swaps for these five ingredients if you can't get your hands on them.
• She says can swap yogurt for buttermilk, melted butter for oil, and mayonnaise for eggs.
• Ptak says you can also use different types of flour and sugar in place of one another respectively.
• Visit Insider's homepage for more stories.

Baking has become one of the many ways people all over the world are dealing with spending so much of their time inside.

While there are loads of recipes to try, like beer bread or fancy cakes, grocery stores may be out of certain ingredients and it may be a week or more before you can get something from a delivery service.

Claire Ptak, author of "The Violet Cakes Cookbook" and owner of the eponymous bakery in London, spoke to Insider about some helpful swaps you can make

Ptak shared her tips for what to use if you can't find some of the most common baking ingredients like buttermilk and eggs.

A lot of recipes call for buttermilk, but if you don't have any plain yogurt is a great substitute

Plain yogurt, like buttermilk, is considered to be a sour dairy so it works as a replacement by offering the same thick texture and tangy taste to your dish.

If you don't have yogurt, but you do have milk and either lemon juice or apple cider vinegar, you can combine the two to get the same effect that buttermilk would have. Both lemon juice and apple cider vinegar have tangy and acidic qualities, which, when combined with milk, help mimic those qualities of buttermilk.

If you're going the milk and acid route, Ptak shared her tip for measuring.

"It depends on how much [the recipe is] asking for," she told Insider. "But let's say it's asking for a cup of buttermilk. You could [measure] a tablespoon of lemon juice first and then fill the measuring cup up the rest of the way with normal milk."

While a lot of cakes and banana bread recipes call for vegetable oil, Ptak says you can make them with melted butter or olive oil

"Oil cake is the most moist, amazing thing," Ptak told Insider. Ptak recommends melted butter as a substitute, and though she warns that it will alter the texture of the cake — it won't be as moist — she says it still works.

If you want to keep that lasting moisture, she also suggested subbing olive oil in for the vegetable oil if you have it.

"You don't want [to use] a finishing olive oil that's a really strong peppery flavor," she said. "Also you don't want to use a really expensive oil. But if it's a good olive oil that you use for cooking, that's a good one to use in a cake instead of veg oil."

If you're saving your eggs for breakfast, bake with mayo — but leave salt out of your recipe

"This is really kind of gross, but I've done it," Ptak said. She recommends using mayo instead of eggs if you don't have any to spare because it acts as a binding agent and will give the cake an amazing texture.

"But what I recommend is that you then take the salt out of the recipe," she continued. "Usually mayonnaise is salty, so you just want to watch that the whole thing doesn't get too salty."

Flours and sugars are mostly interchangeable

When it comes to batters and mixes, Ptak says flour and sugar types can be swapped out for one another. So if a recipe calls for almond flour, but you only have all-purpose, you can use it anyway. The same thing goes for sugar. For example, if you don't have brown sugar, you can swap for regular granulated sugar, and vice versa.

The only times this won't work, Ptak said, is for more complicated confections like caramels. For something like that, she said you can't use brown sugar the same way you'd use regular sugar. But for cookies and cakes, it's perfectly OK.

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• 11 baking fails to make you feel better about yourself
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