Preheat oven to 165 degrees. Grease a 10-inch Bundt pan and set aside. In a large heatproof bowl, add boiling water, butter, dates, sugar, cinnamon, eggs and vanilla. Mix thoroughly until well combined.
In a separate bowl, mix together flour, baking soda and salt. Next, add this to the wet ingredients and mix until completely combined. Add pecans and continue to stir until mixed through evenly.
Pour mixture into prepared tin and bake in oven for approximately one hour. After 45 minutes, check with a skewer to assess remaining time.
After taking out of the oven, loosen the edges of the cake and leave to cool in tin for 15 minutes before taking it out and placing on a wire rack to cool completely.
To serve, cut into thick slices and drizzle with custard. Can be warmed up before serving in oven briefly.