To prepare the cake, place the chopped dates in a heatproof bowl. Pour boiling water over the dates and stir in the baking soda. Cover the bowl and allow to sit for 30 minutes.

Preheat oven to 350°F.  Generously butter a Bundt pan (or 9- x 13-inch baking pan).

After 30 minutes, blend the date-water mixture in a food processor or blender until smooth.

In a large bowl, combine the melted butter and sugars. Whisk in the eggs, one at a time, mixing well between additions, and then add the salt. Stir in the flour, then the date purée. Pour the batter into prepared pan.

Bake at 350°F for 45–50 minutes (25–30 minutes for a 9- x 13-inch pan) or until a toothpick inserted in the center comes out clean. Remove from oven and allow the cake to cool. Transfer to a serving plate.

To prepare the sauce, combine the butter, cream, sugar, and vanilla in a large saucepan over medium heat and bring to a simmer.

Continue simmering for 10 minutes, whisking often, until the mixture thickens and turns a deep amber color.

Drizzle toffee sauce over the Bundt cake and sprinkle with Maldon sea salt, or cut individual slices and drizzle each one with the toffee sauce and a pinch of sea salt.