Combine water, half-and-half, molasses, sugar, coffee granules, ginger, cinnamon, allspice, and cloves in a small saucepan. Heat over medium-high heat, stirring occasionally, until coffee and sugar dissolve and mixture comes to a simmer.

Stir in rum.

Pour into mugs and top with whipped cream and additional coffee granules. Serve with cookies.

Note: If you’d prefer a non-alcoholic cocktail, omit the rum (or let guests add their own).