To cook the salmon, heat a trickle of olive oil in a non-stick frying pan over a medium heat. Season the salmon with salt and freshly ground pepper.
Add a knob of butter and once it is bubbling add the salmon, cooking gently for 3-4 minutes. Turn over and remove the pan from the heat. The heat from the pan will continue to cook the salmon while you make the rest of the dish.
Cook the asparagus and lasagne in a large pot of boiling salted water. They should only take 3-4 minutes. If the lasagne takes longer (check packet instructions) start it off, and add the asparagus part of the way through.
Once they are both cooked, drain well.
To make the hollandaise, place the egg yolk and lemon juice in a screw topped jar or small bottle and shake really well for about 30 seconds.
Pour in half of the butter and shake for a further 30 seconds and then add the remaining butter, leaving the white milky residue behind.
Shake again until the sauce has thickened to a creamy consistency. You can also make the hollandaise by blending in a small blender/processor rather than using a jar, but for these small quantities, using a jar is easier.
To finish the hollandaise, whisk the egg white to soft peaks and then pour in the hollandaise, pinch of salt and cayenne pepper and the chopped chives. Fold together until you have a light sauce.
To serve the dish, sit one sheet of pasta each onto a warm plate, top with the salmon, then the asparagus (leaving some spears aside to garnish the top) and a spoon of hollandaise.
Lay the second sheet of pasta over the top, spoon over the remaining hollandaise and finish with some asparagus spears to garnish the top.
Serve immediately.