Preheat the oven to 350°F (175°C). Grease and flour an 8-inch square cake pan.
In a blender, combine the chopped dates, baking soda, and boiling milk. Blend until the mixture reaches a smooth consistency. If you prefer not to use a blender, you can alternatively place the chopped dates, baking soda, and boiling milk in a bowl, let them sit for about 10 minutes to soften, and then mash them with a fork until well combined.
In a large mixing bowl, combine the date mixture, softened butter, brown sugar, eggs, and vanilla extract. Whisk the ingredients together until smooth, or for an even more effortless blending, you can use an electric mixer.
Next, incorporate the all-purpose flour, baking powder, and salt into the mixture. Stir everything together until a thick and uniform batter forms.
Line the square pan with parchment paper and pour the batter into the pan. Smooth the top with silicone or an offset spatula.
Bake for 35 minutes or until a toothpick inserted into the center comes out clean.
Let the cake cool in the pan for 15 minutes, then take a toothpick or fork to poke holes evenly across the top. These holes will enable the toffee sauce to seep into the cake, infusing it with a rich and decadent flavor.
While the cake is cooling, melt the butter in a saucepan. Stir in the heavy cream, brown sugar, and vanilla.
Bring to a gentle boil and cook, stirring constantly, for 3-4 minutes or until the sauce thickens.
Pour the warm sauce over the cooled cake just before serving.
