In a large sauté pan, melt butter, and then add orange juice, water, brown sugar, nutmeg, and cinnamon. Bring to a boil.
Add orange liqueur, and flambé until alcohol dissipates. Simmer for an extra minute before adding pineapple rings. Simmer for an additional 10 minutes with the pineapple, turning occasionally.
Place the pineapple rings on a plate and then divide the sauce between the servings, filling the core space (reserve a little to drizzle as a garnish).
Top each pineapple ring with a scoop of vanilla ice cream and a dash of orange zest. Drizzle the extra sauce on top, and garnish with a sprig of mint.