Line an 8x8 baking pan with non-stick baking paper, leaving a little overhang for easy removal. Preheat the oven to 180 C.
In a small bowl, add the dates and baking soda, then top with the boiling water. Stir, cover and set aside for the dates to soften.
In a mixing bowl, beat the butter and sugar with a hand mixer on low-medium speed until pale and creamy, then add the eggs and vanilla. Beat briefly to combine.
Sift in the flour, baking powder and salt, if using. Fold gently to combine, the mixture will now be thick and sticky. Add the dates along with all the liquid in the bowl. Gently stir to combine into a smooth batter, running the hand mixer through it if needed.
Pour into the prepared pan and bake for 30 to 35 minutes until a toothpick poked into the center of the cake comes out clean, or with a few moist crumbs. Let it cool in the pan for 15 minutes, then poke holes all over the cake with a toothpick or preferably, a skewer.
In the meantime, make the sauce by combining the sugar, cream, butter in a small saucepan on low heat. Stir often till the butter and melted and the sauce looks uniform, then simmer for a minute or two and turn off the heat. Stir in the salt and vanilla.
Pour about two thirds of the hot sauce over the cake. It will pool a little at the edges so use a spoon to spread it around evenly since the sauce isn't super runny (it doesn't soak inside fully). Let the pudding rest for about 15 minutes, then slice into 16 squares and serve each one with a little bit of the remaining sauce. Whipped cream or vanilla ice cream can be added on top too!
Store the pudding in the fridge at all times, where it will keep for 4 to 5 days. Refrigerate leftover sauce separately and microwave along with the individual portions of the cake before eating. Happy baking!