Heat Instant Pot using saute and add oil. Add onions and mushrooms to Instant Pot and saute for 2 minutes.
Turn Instant Pot off, add garlic, paprika and nutritional yeast and heat for 1 minute.
Stir in water, dairy-free milk, salt, pepper and macaroni noodles
Set Instant Pot to manual for 6 minutes. Once cooking is complete, release pressure immediately.
Stir in the vegan cheddar cheese until it melts and pasta thickens.
Garnish with sliced green onions, if desired.