Pour the milk and the pouring cream into a saucepan, add the vanilla pod and bring slowly to the boil. Whisk the eggs, cornﬂour and sugar together in a bowl and stir in the hot milk and cream.
Place the bowl over a saucepan of gently simmering water, making sure the bottom of the bowl does not touch the water, and stir until the custard thickens enough to coat the back of the spoon. Strain through a nylon sieve into a clean bowl. Cover the surface of the custard closely with plastic wrap, to prevent a skin from forming, and leave to cool.
Reserve a few strawberries for decoration. Slice the remainder and put them in a bowl with the sherry and 3 tablespoons of the icing sugar. Mix together and set aside.
Cut the Madeira cake into three horizontal layers and sandwich together with the jam. Cut into thin slices and arrange in the bottom and slightly up the sides of a glass bowl. Cover with the strawberries and their juice. Pour in the custard, cover the bowl and leave in the refrigerator for at least 2 hours, or overnight.
Whisk the thick cream with the vanilla and the remaining icing sugar until it holds a soft peak. Spread on top of the triﬂe. Slice the reserved strawberries and use, with the toasted almonds, to decorate the top.