Heat the water, milk and butter in a saucepan and melt together. Stir in the salt and flour and mix together to form a roux and cook for a minute. Allow to cool down slightly then place into a mixer, add in the eggs gradually and mix to a soft paste. Pipe into 2 rings on non-stick paper, sprinkle over the flaked almonds and bake in the oven at 170°C for approximately 40 minutes (Do not open the door before 30 minutes) Remove from the oven and allow to cool down completely then cut in half horizontally. Whip the double cream then whisk in the biscoff spread. Spoon the cream filling into the choux rings, sprinkle over the toasted hazelnuts and place on the top. Dust with icing sugar and chill before serving.