Preheat the oven to 180C/356F. Grease and line a 20cm cake pan (not a spring form as the batter is on the thinner side).
In a medium mixing bowl, whisk the flours and almond meal with the baking powder, salt and lemon zest. Set aside.
Add the oil, eggs, sugar and vanilla bean paste to a medium bowl or the bowl of your stand mixer. Use hand beaters or the whisk attachment to cream the mixture until pale in colour and light and fluffy in texture. It should have grown in volume and look aerated. This will take 2-3 minutes.
Add in a quarter or so of the flour, and beat on low to combine. Add a quarter or so of the milk and beat until combined. Continue this pattern until you have used all the ingredients, finishing with flour. The batter should be quite thin - about the consistency of a thinner custard.
Pour the batter into the prepared cake tin. If you’re adding some fruit, add it gently now. I found that berries tend to sink, whereas thinly sliced apple stayed afloat.
Bake the cake for 30-40 minutes (toppings dependent) or until golden brown and cooked through. Cakes with a top layer of fruit will take longer than plain cakes. You can lightly tent the cake with foil if it is taking on too much colour.
Once cooked, allow the cake to cool before running a knife around the edge. Gently invert the cake from the tin, peel off the cake liner and place it on a cooling rack to cool. Serve warm or cooled. Leftovers keep well in an airtight container on the bench.