Bring a large pan of salted water to the boil and cook the asparagus for 2 minutes. Use a slotted spoon to remove the asparagus onto a chopping board. Leave to cool slightly.
Bring the water back to the boil and cook the pasta according to instructions.
Meanwhile, heat 1 tablespoon of olive oil in a frying pan or casserole and cook the chopped garlic for 2-3 minutes over a medium heat.
Add the creme fraiche, peas, lemon juice, Grana padano, chopped dill, salt and pepper. Cook for 3-4 minutes.
Using a sharp knife cut up the apsaragus stalks into small pieces but leave the spears whole.
Add the chopped asparagus stalks and flaked hot smoked salmon to the creamy sauce and stir to combine.
Drain the pasta (reserving 1 cup of pasta cooking water), then add the pasta to the sauce, along with as much pasta cooking water as you need to make the sauce glossy and smooth.
Serve with the reserved asparagus spears, more chopped dill and an extra grating of grana padano.