Preheat the oven to 200C/180C Fan/Gas 6. Line a 2lb loaf tin.
Add the chopped dates, boiling water and baking soda to a small saucepan and heat on low for about 10 minutes, then stir in the treacle. Mash everything together using the spoon, or a stick blender if preferred, and set aside.
In a large bowl, or the bowl of a stand mixer, combine the butter and both sugars for about 3-5 minutes, until fully combined.
Add in the eggs, one at a time. Then add the date mixture and combine again. Fold in the flour.
Pour the mixture into the lined loaf tin and bake about 40-45minutes. Check it at 30 minutes, it may need to be covered with tin foil if the top is browning too fast. Once a skewer inserted comes out mostly clean (it will still be a little sticky in the middle) remove and let cool on a wire rack. Once cool, make the sauce/buttercream:
Make the sauce by combining the butter, sugar and cream on a low heat until it all combines. Then turn up the heat so it bubbles for 3/4 minutes. Turn the heat off and let cool a little. It'll thicken as it cools.
Meanwhile, make the buttercream by combining the butter and sauce in a large bowl/the bowl of a stand mixer. Whisk on high until soft. Add about half of the icing sugar and whisk to combine. Add the remaining icing sugar and whisk to reach a spreadable consistency. Spread over the cake.
At this point, the caramel sauce should have thickened and cooled a little, drizzle this over the cake and decorate with any additional sprinkles etc that you like! Slice to serve.