Preheat the oven to 325℉ Convection / 350℉ regular (165°C fan/ 175°C conventional)
Grease a medium sized baking dish (equivalent of about about 8-10” round)
Add the dates, vanilla, bicarb/baking soda and salt into a bowl and cover with the boiling water. Let soak for 15-30 minutes.
Cream the butter and sugar until well combined.
Mix in the eggs and flour.
Gradually add in the date mixture with its liquid. Doesn't matter if it splits a bit.
Pour the mixture into the baking dish and bake for 35-50 minutes until a toothpick comes out clean. (If you have a smaller dish, it'll be thicker and take longer; larger dish and it'll be on the shorter side of time.)