Prepare the chai spice mix: Combine cinnamon, cardamom, ginger allspice, cloves and black pepper. Mix well until incorporated.
Pour muscle milk into a small saucepan. Heat, stirring often until it reaches a gentle boil. Remove from heat and add black tea. Let steep for 3 to 4 minutes. Whisk in ½ teaspoon of prepared chai spice mix.
Pour into a mug. Add espresso (optional) and serve immediately.