This Kaffir Lime / Makrut Lime Cake is a straightforward, butter-free cake with a subtle lime flavour and wonderfully unique aroma of kaffir lime leaves. This beautiful cake combines the citrus flavours of a regular lime/lemon with kaffir lime leaves infused oil, resulting in a moist and tender texture that will leave you wanting more.

A comforting year-round Thai inspired cake to bake whenever you come across fresh kaffir lime leaves at the supermarket or you have a friend who has a kaffir lime tree, like I do.

Thanks to Rekha, my dear friend, who has a luscious kaffir lime tree in her lush green backyard and is always happy to share her leaves and fruits with me.

The kaffir lime leaves (also called Makrut lime Leaves) are a natural ingredient used as a cooking staple in authentic Thai cooking. They grow on Kaffir lime trees and are widely used in soups, stews, curries, noddle dishes and fish cakes. They are used in the same way as curry leaves in India, thyme in Italy and bay leaves in the west.

The leaves are thick, glossy and dark green on the upper surface with a paler, matte, and porous underside. The leaves have a distinctive physical appearance resembling a butterfly shape (like an hourglass), the two leaves joined end to end like figure-eight.

The leaves have a distinctly citrus flavour with a unique blend of lime, lemon and subtle floral or mandarin – orange notes. The leaves are also used to add subtle citrus taste to baked goods offering a sensory experience like no other.

As the leaves have an intense flavour, they must be used sparingly at first and then adjusted to taste.

The fruit of a Makrut tree is called a kaffir lime/makrut lime. It is a golf ball sized, round to oval shaped (3 to 7cm in diameter), bumpy rind citrus fruit with a bright yellow green skin. The fruit is almost juiceless and is not commonly eaten due to its bitter, acidic and intense flavour. Although the kaffir lime is not edible, it is used to make marmalades, pickles, chutneys and sauces.

The grated rind of the unripe fruit is used for flavouring in cakes, icings, curry pastes, stews, stir-fries and also muddled into cocktails or steeped into tea.

Unlike the fruit, kaffir lime leaves are easy to source all through the year, therefore in this recipe, I will be using the leaves to infuse their delicate scent into the oil, and the oil is then used as a fat in making this Kaffir Lime Cake.

Most of the ingredients in this Kaffir Lime Cake are cupboard staples, except for the Kaffir lime leaves, which can be easily purchased from any large supermarkets and Southeast Asian grocers.

A good tip for effortless baking is to measure the ingredients precisely. A kitchen scale makes all the difference. Another tip is to bring the kaffir lime leaf infused oil and eggs to room temperature before use.

The ingredients yield an honest little cake that reminds us of how even the most basic ingredients can serve up a delicious treat!

Here’s what goes into making the Kaffir Lime Cake:

• Vegetable oil – The richness of butter is not essential for this cake and hence the choice of oil. The key in this recipe is to use oil instead of butter because oil is 100% fat and is lighter than butter. Oil gives this cake a tender texture while keeping it moist for longer, and a longer shelf life. Use a neutral flavoured oil such as vegetable oil, canola oil, or sunflower oil.

• Fresh Kaffir lime / makrut leaves – The star ingredient that adds a subtle, slightly floral, unique citrus flavour and aroma. Unfortunately, you can’t just add them to cake batter on their own. Their flavour has to be infused into oil, and the oil is then used in a simple cake batter. Here, I have steeped the leaves in heated vegetable oil for 1 hour to infuse it with the delicate citrus scent. Substitute: Zest of 1 kaffir lime (during season – March – August in Australia but hard to find!). Important: If you are using zest of a kaffir lime, please add the zest as a substitute to kaffir lime leaves. Recipe Note: There is no need to steep the zest in oil. Add the zest to the flower mixture in Step 4 until just incorporated. There is also no need to add the zest of a lemon / regular lime, if you are using the zest of 1 kaffir lime.

• Plain flour / all – purpose flour – Make sure to measure the flour correctly with a food scale or using a spoon-and-level method for accuracy. For best results, sift the flour first along with baking powder and salt. Sifting also aerates the flour which will give you a light textured cake.

• Lemon / regular lime – You will need only the zest of one lemon or lime. The zest adds citrus notes and lifts the flavour of kaffir lime leaves, making the cake taste delicate yet complex.

• Baking powder – As we are using plain flour / all-purpose flour, baking powder ensures a consistent rise.

• Salt – I have used 2g of iodised saxa salt because that’s what I use. You may use table salt but use less than ½ tsp.

• Natural yogurt – Keeps the cake moist. I have used Greek yogurt because that’s a staple in my home. Substitute: Same quantity of any natural yogurt, lactose free yogurt, low fat yogurt but not flavoured yogurt.

• White / granulated sugar – White sugar is crucial for that soft, moist and visually appealing golden-brown crust. Substitute: 200g caster sugar.

• Eggs – Eggs can vary in size, and I have used 3 jumbo eggs at room temperature (75g x 3) but you may use large (52g x 3) or extra-large (60g x 3) eggs. For proper emulsification and to ensure a good texture, add one egg at a time and mix well until adding the next.

• Desiccated coconut – I have used unsweetened desiccated coconut for a slight tropical flavour.

• 2 tsp. extra vegetable oil or spray: To grease the pan. Substitute: 2 tsp. melted butter for more flavour, but flavour is not essential for this cake, so oil works just as well.