1. Melted butter
1 cup
melted butter, cooled
Best swap: Melted butter. Use 1 cup melted butter, cooled per 1 cup.
Vegetable oil is a neutral liquid fat that keeps bakes moist. Any other neutral oil or melted solid fat can take its place; applesauce can cut the fat if you want.
Melted and cooled butter or melted coconut oil both swap one-to-one and keep bakes moist. To cut fat, replace up to half the oil with unsweetened applesauce.
Yes, melt and cool the butter and use it cup for cup. It adds flavour, though the crumb can be very slightly less moist than with oil.