Preheat the oven to 170C/325F/Gas 3.
Place the dates in a small bowl, pour the liqueur over them and leave them to soak for 15 minutes.
Place the pecans on a baking tray and toast them for 8 minutes - use a timer so they don't get over-cooked.
Make the cake: Take a large mixing bowl and first sift in the two flours, baking powder and cinnamon. Keep the sieve held high to give the flour a good airing, then tip the grains from the maize flour in to join the rest.
Next, add the caster sugar, Ricotta, melted butter and water and whisk with an electric hand whisk until everything is thoroughly blended (about 1 minute). Fold in the nuts, dates and the liqueur in which they were soaking.
Fold everything in thoroughly, spoon the mixture into the prepared tin and smooth the top with the back of a spoon. Scatter the demerara sugar evenly over the surface, then pop the cake into a preheated oven on the middle shelf, where it will take between 1¾ and 2 hours to cook.
When it's cooked it will feel springy in the centre when you make a very light depression with your little finger. If it's not cooked give it another 10 minutes and then do another test.
Remove the cake from the oven, allow it to cool in the tin for 15 minutes, then remove it from the tin and leave to cool completely on a wire rack. Store in an airtight tin.