Preheat the oven to 350°F. Line the sides and base of a 13 x 9 x 2 inch baking pan with aluminum foil or baking parchment.

Melt the butter and dark chocolate together in a large heavy-based pan over a low heat. In a bowl or large measuring cup, beat the eggs together with the superfine sugar and vanilla extract.

Allow the chocolate mixture to cool a little, then add the egg and sugar mixture and beat well.  Fold in the flour and salt.  Then stir in the white-chocolate buttons or chopped white chocolate.  Beat to combine, then scrape and pour the brownie mixture into the prepared pan.

Bake for about 25 minutes. You can see when the brownies are ready because the top fries to a slightly paler brown speckle, while the middle remains dark, dense, and gooey.  Even with such a big batch you do need to keep checking on it: the difference between gungey brownies and dry ones is only a few minutes. Remember, too, that they will continue to cook as they cool.

To serve, cut into squares while still warm and pile up on a large plate, sprinkling with confectioners’ sugar pushed with a teaspoon through a small sieve, and dotting with birthday candles, as you go. Set alight and enjoy the festive scene.

Preheat the oven to 350 degrees F. Grease a 9x9-inch baking pan.

Whisk together 1/3 cup of the water, the oil, eggs and 2 tablespoons of the espresso powder in a large bowl. Add the brownie mix and stir until well blended. Stir in the chocolate chips. Transfer the batter to the prepared baking pan. Bake until a toothpick inserted into the center of the brownies comes out with a few moist crumbs attached, about 35 minutes. Transfer the pan to a wire rack to cool completely.

When the brownies are cool, dissolve the remaining 2 teaspoons of espresso powder in the remaining 2 tablespoons of water in a medium bowl. Whisk in the vanilla. Add the confectioners' sugar and the butter and whisk until smooth. With the brownies still in the pan, pour the glaze over the brownies. Refrigerate until the glaze is set.