There are some situations where I struggle to apply cold solid butter which is hard to spread on the breads/sandwiches. I usually cut in small pieces, keep in between breads and microwave them. How to handle, when I do not have access to microwave. (Even microwave also will not help them to spread evenly on the entire area)

Usually I keep it under sunlight for sometime, but during early breakfast and winter it will not work. This will take time as well.

How to overcome this scenario?