Step 1: Preheat your oven to 180°C (350°F) and grease a 20cm square baking dish. Place the chopped dates and baking soda in a bowl, pour over the boiling water, and let sit for 10 minutes.
Step 2: In a large mixing bowl, cream together the softened butter and dark muscovado sugar until the mixture is light and fluffy.
Step 3: Beat in the eggs one at a time, followed by the vanilla extract. If the mixture starts to curdle, add a tablespoon of the flour.
Step 4: Gently fold in the remaining flour, then stir in the date mixture (including the water) and half of the chopped pecans until just combined.
Step 5: Pour the batter into the prepared dish and bake for 35-40 minutes, or until a skewer inserted into the center comes out clean.
Step 6: While the cake is baking, make the sauce by combining butter, brown sugar, and maple syrup in a saucepan over medium heat. Stir until the sugar is dissolved, then add the heavy cream and simmer for 3 minutes.
Step 7: Once the cake is out of the oven, prick it all over with a fork. Pour half of the warm sauce over the cake and sprinkle with the remaining pecans. Serve warm with the extra sauce on the side.