1-Begin by combining 120g sugar, 30g cornstarch, and 1/4 tsp salt in a saucepan, then whisk in 480ml heavy whipping cream and cook over medium heat until thick and bubbly.

2-Next, reduce the heat and cook for 2 more minutes before removing from heat. Temper the 6 large egg yolks by slowly adding the hot mixture while whisking, then return it to the pan, bring to a gentle boil, and cook for 2 minutes. Stir in 28g butter and 1 tsp vanilla extract, cool the mixture, cover it, and chill it in the fridge.

3-Preheat your oven to 350°F (175°C) and grease and line three 8-inch pans. In a bowl, beat 120ml canola oil, 200g sugar, the separated egg yolks, and 1 tsp vanilla extract until smooth. In another bowl, mix 240g all-purpose flour, 1 1/2 tsp baking powder, and 1/2 tsp salt, then add this alternately with 240ml buttermilk to the wet mixture. Beat the egg whites to stiff peaks and fold them gently into the batter, divide it evenly among the pans, and bake for 25-30 minutes. Let the cakes cool completely on a wire rack.

4-Once cooled, prepare the frosting by beating 85g butter and 1 tsp vanilla extract until creamy, then gradually add 240g confectioners’ sugar until smooth. Whisk the chilled custard until fluffy, layer the cake with custard between the layers, and frost the sides and top. Pipe any remaining frosting on the edges for a polished look, then sprinkle turbinado sugar evenly on top and caramelize it with a kitchen torch about 2 inches above the cake while rotating it for an even, crunchy finish. Serve right away or refrigerate for up to 1 hour.