Grease and line a 9x9 baking dish (metal is preferable) with parchment paper with overhang (if you plan to remove the cake from the tin for serving).

Preheat the oven to 350°F.

In a large bowl, combine the vegetable oil and sugar and whisk until incorporated.

Add the eggs one by one, mixing with beaters (or by hand) to fully incorporate before adding another then whisk for a full minute, until it’s light and creamy.

Add the salt, vanilla and passion fruit pulp, and whisk until combined. Add the sour cream and whisk again.

In a separate bowl, whisk together the cake flour, powdered sugar and baking powder.

Add the dry ingredients and fold into the batter with a rubber spatula until smooth. Pour into the prepared pan.

Bake for 40-48 minutes, until a cake tester comes out clean and the top is golden brown.

In a heatproof bowl, add all of the passion fruit curd ingredients except the butter. Beat together with a silicone whisk.

Place the bowl over a bain-marie (a saucepan with one inch of water in the bottom that does not touch the bowl when the bowl is placed on top) over medium heat.

Cook, whisking constantly, until thickened, this can take 10-15 minutes. Once thickened, remove the bowl carefully from the heat. Add the butter and stir until the butter is completely melted in and combined.

Pour into a clean, heat-proof bowl and cover with plastic wrap or parchment, making sure it touches the surface to prevent a skin forming. Cool in the refrigerator until completely chilled.

Make the vanilla bean mascarpone whipped cream

In a stand mixer or large bowl with beaters add the mascarpone and ⅓ cup of the heavy cream. Beat together until there are no lumps. Remove this mixture to a separate bowl.

In the bowl you whipped in, add the rest of the whipping cream, powdered sugar and vanilla bean paste. Beat until stiff peaks.

Add the beaten mascarpone into the whipped cream. Beat just until combined.

At this point, you can either slice the cake in half to fill it or leave it whole and just top it with the curd and cream. I chose to slice mine in half to fill it for more filling in each bite.

Slice the cake in half with a sharp serrated knife to make two even layers.

Pipe or spoon a border of the cream on top of the bottom layer. Fill with some of the passion fruit curd. Place the final layer of cake on top.

Pipe or spoon as much or as little of the mascarpone whipped cream on top (you may have some leftover) and spoon on the remaining passion fruit curd. Decorate with passion fruit halves and fresh flowers, if desired.