1. Preheat oven to 175C (195C conventional). Grease and line the sides and base of a rectangular baking tin (about 28cm x 23cm x 5cm deep) with baking paper.
2. Sift the flour,cornflour,baking soda and salt into a bowl and set aside for the time being.
3. Combine the butter,sugar,cream cheese and orange zest in the bowl of an electric mixer fitted with the paddle attachment. Mix on medium-high speed until light and creamy (about 2 minutes). Scrape the bottom and sides of the bowl with a spatula from time to time to make sure there are no lumps of butter or cream cheese.
4. Add the eggs,one at a time,and beat on medium-low speed. Again,scrape the bowl to ensure even mixing after each addition. Add the vanilla extract and passionfruit pulp,mix for a few seconds,then fold in half of the sifted dry ingredients. Mix on low speed until partially incorporated,then add the remaining dry ingredients. Blend for 10 seconds,then remove the bowl from the mixer and finish mixing by hand with a spatula.
5. Scrape the mix into the prepared tin and place in the oven. Bake for about 30 minutes,or until a skewer inserted into the middle comes out clean. Allow the cake to cool completely in the tin before turning out. (If you're taking it to a picnic,leave in the tin.)
6. To prepare the glaze,place all ingredients in a medium bowl and beat with a wooden spoon until fully combined. Spread over the cake using a small spatula. Allow the glaze to set before slicing into squares and garnishing with berries for serving.
*Tip: The success of this plain but beautifully textured cake lies in having the butter,eggs and cream cheese at room temperature. Cold ingredients don't emulsify or come together very efficiently,resulting in a clumpy batter and dense,under-aerated cake. Bring the ingredients out of the fridge about an hour before you begin baking (or two,on a cold day).