Cream together the butter and caster sugar in a stand mixer for 10 minutes. Scrape the mixture down the side of the bowl at least once during mixing.
Add one egg then mix for 3 minutes. Then add the next egg and repeat until very light and fluffy.
Combine the flour, cinnamon, and chipotle powder in a separate bowl.
In a separate small bowl, add the chopped dates and boiling water, then mix the baking soda together with the mixture. (You can blend this mixture with a stick blender now if you like a darker sponge with no bits.)
Add all of the flour mixture and the date mixture to the egg, butter, and sugar mix then fold carefully with a spoon. Be careful not to over mix.
Pour the mixture into a square cake tin and cook in the center of the oven for 40 minutes.
Making the chipotle toffee sauce
While the cake is cooking place a saucepan over medium heat and combine all of the toffee sauce Ingredients.
Cook slowly until turns to a golden brown color (around 20 minutes on a low simmer.)
Pulling it all together
Remove the cake from the oven when ready and pour half of the toffee sauce over the cake and allow to soak in.
Serve in squares while still warm and pour some of the remaining sauce over each serving.