Whisk the flour, protein powder, baking powder, and a pinch of salt in a small bowl. Add the egg, half of the Greek yogurt, and half of the honey. Mix until combined, then gently fold in about half of the raspberries.

Spray a large microwave-safe mug with cooking spray and pour in the batter. Microwave for 30–60 seconds, then continue cooking in 10-second intervals until the cake begins to pull away from the sides and the top looks firm and dry. Microwave times may vary, so check frequently and avoid overcooking, as this can make the cake dry.

Let cool slightly, then top with the remaining Greek yogurt, honey, and raspberries. Serve.