Millionaire's shortbread

Set the oven to 350F and line a nine by nine inch baking pan with parchment paper.

Cream 226 g room temperature unsalted butter.

Mix in 50 g granulated sugar until well incorporated and fairly light and fluffy, without going crazy.

Add one egg yolk, half a teaspoon salt and one teaspoon vanilla and mix, scraping the bowl down.

Add 240 g flour in a couple of additions and work it in.

Finish by hand with a spatula, smushing the flour and butter together like a pastry dough; overmixing makes the shortbread tough rather than crumbly.

Crumble the dough into the prepared pan and press it into a flat even layer.

Bake at 350F about 22 minutes, until the edges are golden and it is fully set.

For the caramel, put 113 g butter, 210 g light brown sugar, half a teaspoon salt, sweetened condensed milk and light corn syrup in a pot.

Cook over medium heat, whisking, until the butter melts and it comes together uniformly, then on to 225F; it will deepen past a tan taupe to a proper caramel colour, and it goes from perfect to burnt quickly.

Off the heat, whisk in one teaspoon of vanilla.

Pour the caramel over the baked shortbread and smooth it to the corners with a knife or spatula.

Chill in the fridge about 10 minutes, until the caramel is firm.

Melt 250 g semi-sweet chocolate with 80 ml heavy cream in the microwave in 30 to 40 second bursts at a lower power, stirring every few bursts and letting residual heat finish the last pieces; chocolate starts melting at about 90F.

Pour the chocolate over the set caramel and smooth it with an offset spatula, then run the spatula back and forth for waves.

Finish with a very light sprinkle of flake salt, chill, turn out of the pan and cut.