Preheat the oven to 400F.
Rinse the asparagus spears and dry with a kitchen towel.
Take an asparagus and bend to break off the tough woody end. Repeat for the rest of the asparagus spears. Discard the tough ends.
Cut each bacon rasher horizontally into two portions.
Dust your work surface with flour. Roll out the puff pastry into a ten-inch square to a thickness of less than a quarter inch. Using a sharp knife, cut the puff pastry into 15 strips about half an inch wide.
Take an asparagus spear and roll a strip of bacon around it diagonally. Make sure that there is space in between the rolled bacon. Repeat until all the asparagus spears have been rolled with bacon.
Take a bacon-rolled asparagus and roll a strip of puff pastry from end to end. Position the puff pastry so that it alternates with the bacon.
Line two baking trays with silicone mats or non-stick paper.
Arrange the bacon and puff-pastry covered asparagus spears on the baking trays. Keep them two inches apart to allow room for the pastry to puff.
Brush the bacon puff pastry asparagus spirals liberally with the beaten egg.
Bake the bacon puff pastry asparagus spirals for 20 to 30 minutes in a 400F oven. Note that ovens behave differently. A fan assisted-oven will brown the puff pastry and bacon faster than a traditional oven. Check after 20 minutes to see how the bacon puff pastry asparagus spirals are doing. If they still look pale, bake for another five to ten minutes.
Take the baking trays out of the oven. Cool the bacon puff pastry asparagus spirals for a minute or two. Serve while still hot though for best experience.