200g digestive biscuits
395g can sweetened condensed milk
3 egg yolks
1/4 cup icing sugar
Preheat the oven to 160C.
Break biscuits into chunks, put them in a food processor and process into fine crumbs. Melt the butter, stir or process it into the crumbs.
Press the crumbs into the bottom and sides of a 23cm pie plate or flan tin to form a crust.
Wipe out the processor, then finely grate the zest from the limes and squeeze the juice. Reserve the zest of one lime to garnish the pie.
Add the remaining juice and zest to the processor along with condensed milk and egg yolks. Process to combine.
Carefully pour the filling into the crumb crust. Place the pie in the oven and bake for 20-25 minutes or until the filling has just set.
Remove the pie from the oven and cool on a rack, then cover loosely and refrigerate for 2 1/2 hours.
Just before serving, combine the cream and icing sugar in a large bowl. Whip until the cream will just hold its shape. Spread the cream over the pie filling, sprinkle with the reserved lime zest and serve.