Turn your oven on and set it to 350°F (175°C). Grab three 9-inch cake pans. Either grease or flour them well or line the bottoms with parchment paper so the cakes come out easily later.

Put the butter in a large mixing bowl. Use an electric mixer to beat it until it’s smooth and creamy—this should take around 2 minutes. Add the sugar and keep mixing on medium-high until the mixture turns light and fluffy. This part takes 3 to 4 minutes. Scrape the bowl if needed to keep everything even.

Pour in the egg whites slowly, about ¼ cup at a time. Mix well after each addition. Don’t rush—this step helps make the cake light. Scrape down the sides of the bowl so everything blends evenly.

Now mix in the vegetable oil, lavender extract, and clear vanilla extract. Blend until the mixture is smooth and silky. It should look glossy at this point.

In a separate bowl, whisk together the flour, baking powder, and salt. You’re going to add this dry mixture to the wet one in parts, alternating with buttermilk. Start with dry, then buttermilk, and repeat until everything are added, ending with the dry mix. Stir just enough to combine. Don’t over mix or the cake might turn out dense.

Divide the batter evenly among your prepared pans. Use a spatula to level the tops so the cakes bake evenly.

Put the pans in the oven and bake for 35 to 40 minutes. To check if they’re done, stick a toothpick in the center if it comes out clean, the cakes are ready. They should be lightly golden and spring back when gently touched.

Take the cakes out of the oven and let them sit in the pans for 10 to 15 minutes. After that, carefully turn them out onto wire racks to cool completely. Don’t frost them until they’re fully cool.

In a clean bowl, beat softened butter until it’s light and fluffy. Add in the vanilla bean seeds and vanilla extract. Slowly add powdered sugar, one cup at a time, mixing between each addition. Add a bit of milk as needed until the frosting is smooth and spreadable.

Once the cakes are completely cool, spread frosting between each layer. Stack them neatly, and then frost the top and sides of the cake. Use an offset spatula to smooth the frosting. Decorate however you like dried lavender buds, edible flowers, or just a nice swirl pattern.