Sift (A) into a mixing bowl. Rub in shortening. Add in diced butter and rub until mixture resembles breadcrumbs. Mix in water to form a smooth dough. Turn dough onto a floured surface. Shape into a flat piece. Wrap in cling film. Chill the dough for 30 minutes.
Roll out pastry into a rectangular shape of about 3mm thickness. Cut into straight strips of 5cm wide. Brush lightly with beaten egg white. Grease cream horn moulds. With the damp side inwards, turn the strips carefully around the greased moulds. Start with the pointed end of the mould and make sure that the strips overlap the ends.
Place on a greased baking tray. Brush lightly with egg white. Sprinkle some almond nibs over. Bake in a preheated oven at 200ºC for 10-15 minutes or until crisp and golden brown. Allow to cool. Keep in an airtight container before use.
Just before serving, fill the cones with filling and chill in the fridge.
To make creme patisserie filling: Mix (A) and (B) together in a heatproof dish. Place the heatproof dish over a deep saucepan filled with water. Bring water to a boil in the saucepan. Keep stirring the custard with a balloon whisk until thick. Do not let it boil.
Bring custard away from fire and add in the meringue while custard is still hot. Beat in with a balloon whisk. Leave to cool slightly.
Put custard into a piping bag fitted witha star nozzle. Pipe out custard cream into the empty cones. Keep in the fridge to chill before serving.