Preheat the oven to 350°F. Lightly grease a 9x13 pan with nonstick spray.
In the bowl of an electric mixer fitted with the paddle attachment, cream the butter and sugar until light and fluffy, 4-5 minutes.
Add the eggs one at a time and mix well to combine. Add the vanilla and mix to incorporate.
In a medium bowl, whisk the flour, baking powder, and salt to combine. Add the mixture to the mixer and mix just until incorporated. Scrape well to ensure the batter is evenly combined.
Pour the mixture into the prepared baking pan. Bake until a toothpick inserted into the center comes out clean, 38-40 minutes. Let cool completely.
Poke the cake all over with a wooden skewer. Pour the passionfruit juice evenly over the whole cake. In a large container, preferably one with a pour spout, whisk the milk, sweetened condensed milk, and evaporated milk to combine.
Gently pour the mixture all over the cake, letting it soak in through the holes. Most of this will happen quickly, but if some liquid pools up anywhere on the surface of the cake, just spoon it back over the cake until the mixture is absorbed (let it sit for about 30 minutes).
Finish the cake with the whipped cream and the fresh passionfruit pulp. Serve immediately, or refrigerate for up to 5 hours before serving.
I always carry three kinds of hot sauce in my purse. I have a soft spot for making people their favorite dessert, especially if it's pie. My first cookbook, The Fearless Baker, is out on October 24, 2017.