I found this recipe on the Observer website by Hugh Fearnly-Whittingstall - if the sugar is scrapped it seems like it could be pretty Paleo friendly. The reason I was interested is because it contains no egg (which I'm allergic to):
This traditional Ligurian cake contains no gluten or raising agent, so it won't rise like a traditional cake. Instead, it's dense and rich without being too sweet. You can buy organic chestnut flour from shipton-mill.com (£3 for 500g).
5 tbsp extra-virgin olive oil
400g chestnut flour
60g caster sugar
A pinch of sea salt
Zest of an orange
30g pine nuts
1 good pinch fresh rosemary leaves
Preheat the oven to 150C/300F/ gas mark 2. Brush a 22cm springform cake tin (or similar) with some of the oil. Soak the sultanas in hot water for about 10 minutes, so they plump up while you prepare everything else.
Sieve the flour into a large bowl and whisk in the sugar, salt, zest and about 400ml of water. Stir until you have a smooth batter, then add the rest of the olive oil, beating as you add it. Pour the mixture into the tin, scatter over the pine nuts, sultanas (drained and dried) and rosemary, and bake for about 45 minutes.