Line a baking sheet with parchment paper for preparing garnish, if desired. Place melting wafers and coconut oil in a small microwave-safe bowl. Microwave on HIGH at 30-second intervals until melted and smooth, stirring each time. Stir in 10 drops green food coloring gel. Spoon mixture into a sandwich-size resealable plastic bag; close bag and snip off one corner of bag. Pipe mixture into 4 (2- to 3-inch) shamrock shapes on prepared baking sheet; let stand until set.

Add chocolate flavored syrup and ¼ teaspoon mint extract to each of 2 (10-oz.) glass mugs. Add cold strong brewed coffee or espresso to each mug; stir to combine. Add ice; set aside.

Beat heavy whipping cream and sugar in small bowl with an electric hand mixer until slightly thickened. Add whole milk and ½ teaspoon mint extract; beat until combined. Spoon cream foam on top of coffee mixture in mugs. Garnish with the green vanilla-flavored shamrocks.