Get out a microwave-safe mug. I used a 12-oz mug which had enough room to mix without spilling the ingredients, but transferred to a smaller mug for nuking. It doesn't rise much, so as long as your mug holds your batter, you're good.
Add in your dry ingredients - flour, sugar, cooca powder, cardamom and salt and mix with a spoon until just combined.
Then add in the wet- water, butter, and 2 teaspoons tahini paste. Stir again just until combined. The batter should be thick.
Drizzle the last teaspoon of tahini on top and swirl to make it pretty.
Microwave for 60-90 seconds or until the top is set and the inside is still slightly gooey and moist. (Start with 60 seconds and see if you need more.)
Let cool for a minute and top with ice cream, sprinkles, a sprinkle of cardamom and powdered sugar, or whatever you like!