Mango Butter

8 cups peeled and chopped ripe mango
3 cups packed brown sugar
3 tablespoons grated fresh ginger
1 teaspoon grated fresh lime zest
1/2 cup fresh lime juice
1 teaspoon ground cinnamon

Place mangoes in a heavy saucepan over medium heat. Cook, stirring frequently, until mangoes are very soft. (Since mangoes are usually very juicy, you needn't add any water unless the mixture starts to stick; then add up to 1/2 cup, a little at a time, as necessary.) When the mangoes are cooked, remove from heat; pur