Set up a stand mixer with a paddle attachment and preheat oven to 160 degrees Celsius on fan forced.

In a bowl add in caster sugar and orange zest and using your hands, massage the zest into the sugar to allow the oils to come out.

Cube the butter and add in to the bowl. Place bowl in stand mixer and beat with paddle on medium high for 4-5 minutes or until light and creamy.

Add in the eggs and vanilla essence and beat again for a minute to combine.

Mix together the flour, bicarb and salt and then add in half the amount and half the buttermilk into the bowl and on the lowest setting, beat the mixture until just combine.

Add the rest of the flour mix and buttermilk and beat again on lowest speed until just combined.

Line a sheet baking tray (22cm x 32cm) and pour in the batter, smoothing out to make even.

Place in oven and bake for 35 minutes or until a skewer comes out clean.

Remove from oven and allow to cool in tray for 10 minutes. Once cooled remove from tray and place on wire rack to cool completely.

Prep the raspberries and blackberries by washing and slicing down longways.

Once cake has cooled, measure halfway and cut in down the middle to create two squares.

Using a serrated knife, even off the top if it needs it, to make it straight to put the frosting on.

Place one cake slab on serving plate and add half the vanilla buttercream, smoothing it over to the corners.

Squish down the halved berries, pushing into the cream until you have nice coverage.

Place second slab of cake on top and add the rest of the buttercream on top.

Using an offset spatula, smooth to the corners and create little swirl divots.

Add a smattering of berries before finishing off with edible flowers and fennel fronds.

Keep in fridge covered and when ready to serve, allow to sit out and come to room temperature before serving.

If you don’t add the fruit, the cake can stay covered at room temperature for 3-4 days.

For Vanilla Buttercream: Chop the butter into cubes and cream in stand mixer with paddle attachment on medium high for 2-3 minutes or until smooth and aerated.

Add in the rest of the ingredients and begin mixer on low to combine the sugar, and then bring to a high speed and mix for 2-3 minutes, until you have a smooth and glossy frosting.

Leave at room temperature until ready to use.