In 10 ounce wide mug, add the flour, cacao powder, sugar, pinch salt and baking soda. Mix well.
Create a small well in the dry ingredients and add the vanilla extract, plant-based milk, and oil. Mix well until combined. Some lumps are okay.
Lastly, stir in 1 tablespoon of espresso.
800-900 Wattage Microwave: Cook for about 2 minutes and 15 seconds.950-1050 Wattage Microwave: Cook for about 2 minutes.1050-1200 Wattage Microwave: Cook for about 1 minutes and 45 seconds.
Enjoy with scoop of ice cream on top.
Storage: This cake stores well in the refrigerator in an air-tight glass container for up to 3 days. Reheat in the microwave.
Notes
To make this cake gluten free: Bob's Red Mill gluten free 1 to 1 flour works well.
I don't recommend replacing the sugar with maple syrup - the batter will be too wet. If you want to try something less refined, I would use coconut sugar however I have not tested it.