Soften the fats but do not melt completely.
With a whisk, begin beating the fats together until there are no lumps
Add salt and cool pumpkin puree. Begin beating vigorously to avoid lumps and to help fluff it and harden the texture of the fats.
If adding additional flavors, fold those in gently with a spatula.
To make garlic herb flavored option:
1 clove garlic
Smash garlic with the flat side of your knife. Salt heavily. Begin chopping garlic and herbs together very fine until it is almost a paste like texture. Let the mixture sit out in the open air for about a half an hour before mixing into butter.