Choose the right mug: Use a microwave-safe mug that holds at least 10–12 ounces. This gives the batter room to rise without overflowing.

Add the spread and milk: Spoon the chocolate hazelnut spread into the mug, then add the milk. Stir until smooth and glossy. If your spread is stiff, microwave it for 10–15 seconds first to loosen it.

Mix in the flour: Add the flour and a small pinch of salt if you’re using it. Stir until just combined and no dry streaks remain. The batter will be thick and fudgy.

Add extras (optional): Fold in a few chocolate chips or a drop of vanilla. Keep it simple—too many add-ins can make the cake dense.

Microwave: Cook on high for 45–60 seconds, then check. The top should look set but slightly glossy in the center. If it’s still very wet, cook in 10–15 second bursts until just done. Total time is usually 60–90 seconds, depending on your microwave.

Rest before eating: Let it sit for 1–2 minutes. It keeps cooking as it rests and firms up to that brownie texture.

Serve: Enjoy as-is, or top with a small scoop of ice cream, a drizzle of peanut butter, or a sprinkle of flaky salt.