Place the 11-ounce square bittersweet or dark chocolate (broken into pieces) or 2 tablespoons semi‑sweet/dark chocolate chips and 2 teaspoons coconut oil in a microwave‑proof mug. Microwave at 50% power for 30 seconds; stir. If not fully melted, continue microwaving at 50% power in 15‑second increments, stirring after each, until the chocolate is smooth and melted (total usually ~1 minute).

Add 3 tablespoons all‑purpose flour (or white whole wheat flour), 1 tablespoon cocoa powder, and 1/4 teaspoon baking powder to the mug. Stir briefly to combine with the melted chocolate.

Add 2 tablespoons unsweetened almond milk, 1 tablespoon pure maple syrup, 1/4 teaspoon instant espresso powder (optional), 1/2 teaspoon pure vanilla extract (optional), and 1/16 teaspoon (about 6 drops) peppermint extract. Stir with a fork or small whisk until the batter is smooth and evenly combined, scraping the sides and bottom of the mug.

Microwave on high until the cake has risen and the top is just set and no longer wet to the touch, about 1 to 2 minutes (microwave times vary; mine takes 1 minute 15 seconds). Avoid overcooking.

Let the mug cake rest for about 30 seconds to 1 minute (the mug will be hot). Top with coconut whipped cream (or dairy whipped cream), sprinkle mini chocolate chips, and garnish with fresh mint. Serve.