This compound butter is imbued with the flavors that entered Italian cooking during the Renaissance when the spice trade was flourishing. It is excellent on baked, poached, or grilled fish, such as salmon, tuna, and halibut.
Melt 3tablespoons butter in a medium sauté pan over medium heat. Add the onion and cook until tender, about 10 minutes. Stir in the cinnamon and cloves and cook 1 minute longer. Add the red wine and cook over high heat until reduced by half and syrupy. Let cool.