Start with cold heavy cream and mix on high speed.
After about 3 minutes, you'll have whipped cream; continue mixing.
After about 6 more minutes, the butter will clump and separate from the liquid. Strain and wrap the butter in cheesecloth, then squeeze out the liquid.
Tip: To make perfect rounds, shape flavored butter into a log using parchment paper; wrap and chill, then slice.
Pumpkin
Mash 1/4 cup canned pure pumpkin, 1 stick softened butter, 1/4 teaspoon orange zest, 1/2 teaspoon each sugar and pumpkin pie spice, and a pinch of salt.
Spiced Cranberry
Simmer 1/2 cup cranberries with 1 tablespoon water, 1/4 cup sugar, 1 strip lemon zest, 1 cinnamon stick and 1 clove, 6 to 8 minutes. Discard the zest, cinnamon and clove; let cool. Pulse in a food processor with 1 stick softened butter and a pinch of salt.
Bourbon-Raisin
Microwave 1/2 cup raisins with 1 tablespoon bourbon, covered, 45 seconds; let cool. Pulse in a food processor with 1 stick softened butter, 1 tablespoon chopped chives and a pinch of salt.
Sage Brown Butter
Melt 1 stick butter over medium heat and cook until browned. Add 1/4 cup sage and fry 30 seconds; drain on paper towels, then chop. Let the brown butter cool; mash with 1 stick softened butter, the sage and a pinch of salt.