Preheat the oven to 180°C (350°F).

Stir the biscuit crumbs, coconut (if using) and melted butter together until crumbly (test by pinching some mixture between your fingers – if it holds, it’s good. If it’s too crumbly, add a little more melted butter) and press this into an ungreased 9-inch (23 cm) pie plate.

Bake the crust for 10 minutes, then cool before filling.

For the filling, reduce the oven temperature to 150°C (300°F). Whisk the condensed milk with the lime juice, zest and vanilla and then whisk in the egg yolks (save the whites for the meringue). Pour this into the cooled crust and bake for 30 minutes, until the filling no longer jiggles when the pan is moved. Cool the pie to room temperature. Once cooled, the pie can be chilled and topped with meringue later.

Add the four egg whites into a medium mixing bowl. Add the sugar and whisk them together. Heat the mixture on a bain marie – bring a small amount of water to a simmer in a pan that is large enough to accommodate your mixing bowl.

Place the bowl on top of the pan and make sure it doesn’t touch the water. Whisk the mixture for 2-3 minutes until the mixture becomes warm to the touch (if using a thermometer, you’re aiming for 71°C or 160°F).

Remove the bowl and beat the meringue using an electric whisk until its glossy and firm.

Top the pie with the meringue and create peaks with the back of your spatula. Finally, using a kitchen blow torch, lightly brown the top of the meringue (otherwise put it in the oven for 10 or so minutes at about 200°C (400°F) until lightly browned – keep a close eye on it!

If not serving straight away, put back into the fridge and take out about 10-15 minutes prior to serving.