Pre heat the oven to 160°C. Place the hob nobs in to a food processor and blitz until you have similar to breadcrumbs.

Mix the hob nobs in to the melted butter and mix well. With a 23 cm loose bottomed cake tin press the biscuit/butter mix in firmly. This part you may want to take your time with to ensure that the bottom is not to thick, about as thick as a pound coin and that you have a build up on the sides. Bake in the oven for 10 minutes, remove and then cool. If the base has seemed to have risen use the back of a spoon to press down gently.

In a large mixing bowl whisk the egg yolks with an electric whisk for about a minute and then add the condensed milk and whisk for a further 3 minutes. Add the lime juice and zest and whisk for a further 3 minutes. Pour the filling in to the biscuit base and then bake for a further 15 minutes.

Cool and chill for a minimum of 3 hours but is better overnight.

When your ready to serve whisk the cream and sugar to a medium peak. This is where the cream will hold itself but can still be spread, of which then spread over the chilled key lime pie. Finish with the extra lime zest and enjoy.