Kirsten's Millionaire Shortbread Recipe

We churn out roughly 86 slices a week of this in the busy summer months. It does take time and patience it is not a quick, whip-together recipe but it is so worth the effort.

Make sure you take the label off the condensed milk tin before you boil it or the glue will knacker your saucepan.

Be careful not to let the tin boil dry as it will explode. No one wants that in their kitchen …

When you open the hot tin of condensed milk, stab a hole with the tin opener first to release the pressure and avoid burns.

This will keep in the fridge for up to 10 days.

KIRSTEN'S MILLIONAIRE SHORTBREAD
Makes 12 generous slices

For the caramel:
1 x 397g tin of condensed milk
250g salted butter
140g caster sugar
For the base:
330g butter, softened
190g dark brown sugar
350g plain flour
120g cornflour
For the chocolate topping:
400g good quality dark chocolate chips
300g double cream (try Lewis Road)
100g butter
30 x 23cm brownie tin

1. Place the unopened tin of condensed milk, minus its label, in a small deep saucepan. Cover it completely with hot water and boil for four hours, topping up with water so the tin is covered all the time.

2. Preheat the oven to 170C (150C fan). Grease and line your tin with greaseproof paper.

To make the base: Cream the butter and sugar until paler in colour and light and fluffy. Scrape down the sides of the bowl occasionally to help with even mixing. Add the flour and cornflour and mix through until you have one lump of dough. Scrape the dough into your tray and squash it down with your hands to get a roughly even layer. Dip a palette knife in hot water and run it over the top to smooth out the base (a bit of hot water helps move the dough around, but don't overdo it). Bake for 20 minutes, until the base is lightly browned, puffy and biscuity. Set aside to cool.

Now start on the caramel: Once your tin of condensed milk has boiled for four hours, drain off the water. Leave the tin to cool for about 10 minutes so it doesn't burst when you pierce it with a tin opener, then stab a hole with the opener to release any pressure. Put the butter and sugar in a heavy-bottomed saucepan. Fully open the tin and scrape the hot contents into the pan. Place on a high heat and whisk vigorously until the butter melts and the sugar combines with the condensed milk. Keep whisking constantly as the caramel comes to the boil: it will look smooth, thick and volcanic. Be really careful doing this it can splatter. We sometimes use a stick blender instead of a whisk as it moves the caramel around fast, gets rid of any lumps and gives you a really silky finish. Pour the caramel over your cooled base and leave to set.

To make the chocolate topping: Melt the chocolate, cream and butter in a heavy-bottomed saucepan over the lowest heat possible. Stir constantly as it melts and take the pan off the heat as soon as everything is smooth and fully combined. Make sure your tin is on a flat surface and pour the topping over the cold caramel. Leave to set overnight, then cut into 12 slices.

• Recipes taken from The Mountain Cafe Cookbook, a Kiwi in the Cairngorms (Kitchenpress.co.uk).