Select the substitute based on your recipe's needs: butternut or kabocha for roasting, sweet potato or pumpkin for purees and soups.
Prepare the substitute by peeling, cutting, and optionally draining excess moisture, especially for pumpkin and kabocha.
Use a 1:1 substitution ratio to replace acorn squash in your recipe, adjusting cook time if using kabocha squash (reduce by 5 minutes).
Taste and adjust seasoning or sugar levels as needed, especially with sweeter substitutes like butternut squash and sweet potato.
For soups and stews, add softer substitutes like sweet potato later to avoid overcooking and mushiness.