Butter the insides of a 9-in x 13-in rectangular Pyrex baking dish. Line it with parchment paper. Butter and flour the paper, bottom and sides.

In a saucepan, bring the water, dates and baking soda to a boil. Simmer for about 3 minutes, stirring frequently. Transfer to a bowl and let cool.

In a bowl, combine the flour, baking powder and salt. Set aside.

With the rack in the middle position, preheat the oven to 350°F (180 C).

In another bowl, cream the butter and brown sugar using an electric mixer. Add the eggs one at a time, beating until the mixture becomes smooth and creamy.

With the mixer on low speed, add the dry ingredients, alternating with the date mixture. Pour into the pan.

Bake until a toothpick inserted in the centre comes out clean, 23minutes. Remove from the oven. Place the pan on a baking sheet to catch any icing that might spill over. Set the oven to broil (regular broil, not maximum broil).

Meanwhile in a saucepan, heat up butter and cream, then add rest of frosting ingredients. Bring to a boil, stirring constantly. Reduce the heat and simmer gently for about 2 minutes.

Spread the frosting on the hot cake and broil until golden brown, just 2 minutes. Let it cool before slicing and serving.