Make & cool the raspberry sauce. First prepare the raspberry filling according to the recipe here. Allow the raspberry sauce to cool completely and chill for at least 30 minutes before using.

Preheat oven to 350°F. Line the base of two 8-inch round cake pans with rounds of parchment paper.

Sift flour, baking powder, baking soda and salt into a medium bowl and whisk to blend evenly.

Combine soft butter, oil, sugar and vanilla in a large bowl and beat with an electric hand mixer for 2 minutes until pale and fluffy.

Beat in egg until well incorporated, then add egg whites and beat until well combined and smooth. Mix in sour cream.

Sift in half of the flour and mix it in slowly, then gradually beat in half of the milk. Add remaining flour and milk, and beat on high for the last 5 seconds to emulsify the batter. Gently fold in raspberries.

Divide the batter evenly between the prepared pans and bake for 25-30 minutes until lightly golden and a skewer inserted into the center comes out clean.

Transfer pans to a wire rack and let cool for 20-30 minutes in the pan, then run an offset spatula around the edges to loosen them and let cool completely on the racks.

Place chopped white chocolate into a large bowl. Pour ½ cup of cream into a saucepan with the scraped vanilla bean seeds and place over medium heat. Once simmering, immediately pour over the chopped chocolate, cover the bowl and let stand for 2 minutes.

Uncover the bowl and whisk until the chocolate is completely melted and the mixture is smooth. Let it cool for 5 minutes and whisk in remaining cold cream. Place the bowl in the fridge and chill for at least 2 hours or overnight until completely cold.

Once thoroughly chilled, add the vanilla extract and beat with an electric hand mixer until thick and fluffy, about 2 minutes.

Place one cake layer on a serving plate. Fill a piping bag with about 1 cup of frosting and pipe around the circumference of the cake to build a wall.

Spread 1 cup of raspberry filling over the top of the cake within the frosting border. Place the other layer on top and cover the entire cake with frosting.

Use a large offset spatula to even out the sides and make swooshes and swirls on the top layer. Decorate with fresh raspberries.