Bring a large pan of water to the boil and add your pasta of choice. Cook according to the packet instructions.
Whilst the pasta is cooking, add 2 tablespoons of water in the base of a large non-stick frying pan. Add the sliced onion and sauté for 5 minutes.
Remove the woody ends of the asparagus stems. Cut off the tips and cut the stems into bite-sized pieces.
Add the garlic slices to the pan with a little extra water if needed and continue to cook on a medium heat for another couple of minutes.
Pop the chopped asparagus stems into the pan along with the defrosted peas and continue to cook over a medium heat.
Drain the cashew nuts and rinse well. Pop into a high-speed blender jug and add enough water to cover the nuts with an extra 1 cm on top. Add the nutritional yeast, garlic powder, salt and pepper. Blend for 30 seconds until smooth.
Add the aspragus tips to the pan and cook for 2 minutes.
Pour the cashew sauce into the pan and stir well to combine. Simmer on a low heat - take care as the sauce with thicken as the water evaporates so make sure the heat is not up high.
Once the pasta is cooked, drain and add to the pan. Stir well to coat the pasta.
Serve in bowls with the fresh parsley scattered on top. Eat immediately.