Select the substitute based on dish type: acorn or pumpkin for soups, kabocha for roasting, sweet potato for purees.
Peel, seed, and cube substitutes as required; cook by roasting, boiling, or steaming until soft.
Use substitutes at a 1:1 volume ratio replacing butternut squash; adjust seasoning and sweetness if needed.
Blend or mash cooked substitutes to desired texture, thinning with stock or milk if needed for smoother purees.
Taste and adjust seasoning and consistency before adding to your dish to ensure balanced flavors.