Preheat your oven to 180°C (350°F) for a standard oven or 160°C (320°F) for fan-forced. Grease and line two 8-inch round cake pans with baking or parchment paper. In a large mixing bowl, combine the softened butter, oil, and sugar. Using an electric mixer on low speed, mix until combined, then increase to medium speed and beat for 1–2 minutes until the mixture is creamy and pale. Add the vanilla extract, eggs, and honey, then beat briefly to incorporate. Scrape down the sides of the bowl to ensure everything is well mixed.

In a separate bowl, whisk together the flour, baking powder, cinnamon, and salt. Add half of these dry ingredients along with the yogurt and milk to the butter mixture and mix on low speed. Then add the remaining dry ingredients and continue mixing on low speed until the batter is smooth and creamy—be careful not to overmix. Divide the batter evenly between the prepared pans and gently smooth the tops with a spatula. Bake for 25–30 minutes, or until a skewer inserted in the center comes out clean.

Allow the cakes to cool in their pans for 15 to 30 minutes before carefully removing them and transferring to a wire rack to cool completely.

Place the cream and vanilla extract into a large mixing bowl. Using an electric mixer fitted with a whisk attachment (or a hand whisk), begin whipping the cream on low speed, then increase to medium. Watch closely as the cream thickens and becomes smooth, creamy, and cloud-like. Reduce the speed or switch to a hand whisk once the cream begins to thicken. Continue beating until stiff peaks form, then stop immediately to avoid over-whipping. Divide the whipped cream into four portions and refrigerate until ready to assemble.

In a large mixing bowl or stand mixer bowl, beat the softened butter on medium speed for 1 to 2 minutes until smooth and creamy. Add half of the icing sugar, honey, and milk, mixing on low speed initially, then increasing to medium speed until combined (about 1 minute). Add the remaining sugar and beat on low, then medium speed until smooth. Stir in the salt and continue beating on medium speed for another minute until the buttercream becomes fluffy and creamy. Finish by folding the buttercream gently with a spatula to remove any air bubbles.

Using a sharp serrated knife or cake leveller, slice each cake layer in half to create four layers total. Place the first cake layer on a serving plate or cake stand and spread one portion of the whipped cream evenly over it. Repeat with the remaining layers and whipped cream, finishing with the final cake layer on top. You will have one portion of whipped cream left for decorating the top of the cake. Cover the entire cake—top and sides—with the honey buttercream using a small spatula. For a decorative finish, use a piping bag fitted with a large round tip to pipe extra buttercream on top.