In a microwave-safe mug, whisk together flour, sugar, and cocoa powder. Add a tiny pinch of salt to enhance flavors.

Pour in milk, coconut oil, and vanilla extract. Stir until the batter is smooth and free of lumps.

Gently fold in chocolate chips, distributing them evenly throughout the batter.

Drop blueberry jam in dollops on top of the batter. Use a toothpick to create a light swirl, leaving some jam in distinct pockets.

Microwave on high for 60-75 seconds. Cooking time may vary slightly depending on microwave wattage.