Combine the granulated sugar and 1/8 tsp ground cinnamon on a small shallow plate. Brush the rim of a martini or coupe glass with the melted butter, then dip the rim into the cinnamon-sugar mixture to coat. Set the glass aside to dry briefly.

If using a mini churro garnish, warm it slightly (10–15 seconds in microwave) so it's fragrant but not hot.

Whipped Cream Topping

Chill a small mixing bowl and whisk or beaters for a few minutes. Pour in 1/2 cup heavy cream, add 1 tsp powdered sugar and 1/4 tsp vanilla extract. Whip by hand or with an electric mixer until soft peaks form (about 1.5–2 minutes on medium speed). Refrigerate until ready to top the cocktail.

Cocktail Assembly

Bloom mole & cocoa

In a small mixing glass or shaker, add 1/2 tsp unsweetened cocoa powder and 1/4 tsp mole paste (or mole powder). Add the 1 oz freshly brewed espresso and stir vigorously until the powders/paste are fully dissolved and the mixture is smooth. This creates a mole-flavored coffee concentrate.

Add 2 oz Flor de Caña rum, 1/2 oz falernum, 1/4 oz vanilla liqueur (or syrup), 2 dashes chocolate bitters (if using) and a pinch of fine salt to the mixing glass with the mole-coffee concentrate.

Fill the shaker with ice and shake vigorously for 12–15 seconds to chill and slightly dilute. Double-strain into the prepared cinnamon-sugar rimmed coupe or martini glass to remove any mole particles.

Finishing & Garnish

Carefully spoon or pipe a generous dollop (about 2 tablespoons) of the chilled vanilla whipped cream onto the surface of the cocktail so it floats as a cap—this is the 'nightcap' element.

Grate a scant 1 tsp dark chocolate over the whipped cream, then dust very lightly with the remaining pinch of ground cinnamon. If desired, add a tiny extra dash of chocolate bitters over the cream for aroma.

Lean the warmed mini churro or churro stick on the rim of the glass so it rests against the whipped cream. Serve immediately with a small spoon or straw for sipping through the cream.