Preheat the oven to 350 °F (180 °C). Line a 9-inch round cake pan with parchment paper. Slightly oil the paper with oil. Set aside.
Finely chop the pitted dates into small bits. I like to cut each in half lengthwise and then chop in the other direction to form small cubes.
In a large mixing glass bowl, add the chopped dates and boiling water. Cover the bowl with a plate to prevent the water from evaporating. You will use this water in the cake batter. Set aside for 10 minutes.
Bring back the bowl with the date/water mixture - keep the water - and stir in muscovado sugar, orange juice, olive oil, vanilla extract, and 1 tablespoon of orange zest, if you like its tangy flavor.
Add in flour, baking powder, baking soda, salt, and cinnamon. Stir to combine and form a smooth cake batter.
Fold in the chopped walnuts if used, and stir to incorporate evenly.
Pour the cake mixture into the prepared pan.
Bake the cake at 350°F (180°C) on the center rack for 25-35 minutes until a toothpick inserted in the center comes out clean.
Let it cool down for 10 minutes in the pan, then transfer it to a cooling rack. Keep it at room temperature for a few hours before slicing.