In a 2-cup capacity microwave-safe mug whisk together with a fork, the flour, sugar, cocoa powder, baking powder and salt until well combined.

Add in the melted butter, milk, egg and vanilla. Whisk well to combine, making sure to mix in the flour mixture in the bottom.

Place the chocolate pieces in the center of the mug. Do not push down; it will sink as it bakes and then drizzle the tablespoon of water right on top of the batter

Cook in microwave on full power for 1 minute and 20 seconds to 2 minutes or until the cake rises to the top, the edges look set but the center looks ever-so-slighly wet and shiny but not raw, and sticks slightly to the finger when touched. Do NOT overbake to ensure that saucy, molten-y interior. If the center still looks raw then give it another 5 to 10 seconds

Enjoy. Add whipped cream raspberry sauce. Fresh strawberries or just how it is.