In a saucepan, add the egg yolks and sugar. Whisk gently just until combined.

Add the cornstarch, vanilla extract, and whole milk. Whisk until the mixture is completely smooth and lump-free.

In a separate saucepan, heat the coconut milk over medium heat until you see small bubbles forming around the edges. Do not boil.

Slowly pour ⅓ of the hot coconut milk into the egg mixture while whisking continuously. This step tempers the eggs and prevents curdling.

Add the remaining hot coconut milk and whisk until fully combined.

Place the saucepan back on low heat. Cook while alternating between a whisk and a spatula, scraping the bottom and sides constantly. Once the custard thickens to a pudding-like consistency, immediately remove it from the heat.

Transfer to a bowl and press cling film directly onto the surface to prevent a skin from forming. Let cool to room temperature, then refrigerate until ready to use.

Preheat the oven to 180°C / 350°F. Grease and line two 6-inch cake pans.

Sift together the flour, cocoa powder, baking soda, and salt. Set aside.

In a large bowl, beat the eggs and sugar using an electric mixer until pale, frothy, and doubled in volume. Add the oil and vanilla extract and beat until fully combined.

In a small saucepan, gently heat the coconut milk and coffee just until warm. Do not boil.

Add the dry ingredients to the batter in 2–3 additions, gently folding with a spatula after each addition. Once no dry flour remains, pour in the warm coconut milk–coffee mixture and fold gently until just combined.

Divide the batter evenly between the prepared pans. Bake for 42–45 minutes, or until a skewer inserted into the center comes out clean.

Cool in the pans for 5–10 minutes, then demould and cool completely on a wire rack. Level the cakes and slice each horizontally to create 4 layers.

In a heatproof bowl, combine the egg whites and sugar.

Remove from the heat and beat using an electric mixer until the bowl feels cool and stiff peaks form.

Add the softened butter, one tablespoon at a time, beating well after each addition. Continue beating until the buttercream becomes smooth and creamy.

Add the vanilla extract and thick coconut milk/cream and beat until fully incorporated.

Place the first cake layer on a cake stand. Lightly brush or spoon 2–3 teaspoons of coconut milk over the layer.

Pipe a ring of buttercream around the outer edge to create a dam. Fill the center with cooled coconut custard and sprinkle desiccated coconut.

Repeat with the remaining layers.

Apply a thin crumb coat over the entire cake and refrigerate for 20–25 minutes.

Apply the final coat of buttercream. Press desiccated coconut generously onto the sides and top for a snowy effect. Decorate the top with piped buttercream as desired.

Slice and serve.