In a medium bowl, gently whisk the eggs until fully combined. Be careful not to incorporate too much air into the mixture. In a separate bowl, mix the dashi, soy sauce, mirin, and salt. Slowly combine the dashi mixture with the eggs, whisking gently to ensure a smooth consistency. Strain the mixture through a fine sieve to remove any clumps or bubbles for a silkier custard.

Prepare the filling ingredients by slicing the mushrooms and kamaboko, and cutting the chicken into small bite sized pieces. Season the chicken lightly with salt. Place a few pieces of shrimp, chicken, shiitake mushrooms, and kamaboko in each individual serving cup or ramekin.

Pour the egg dashi mixture over the fillings in each cup, leaving a little space at the top for expansion during cooking. Add a ginkgo nut to each cup if desired.

Cover the cups with a piece of aluminium foil to prevent the surface from drying out during steaming. Prepare a steamer by bringing water to a simmer over medium heat.

Once the water is simmering, place the cups in the steamer. Make sure the water is not boiling too vigorously, as it may cause the custard to become too firm or develop bubbles. Steam for 10-12 minutes or until the custard is set but still slightly jiggly in the centre.

Check the consistency by inserting a toothpick into the centre of the custard; it should come out clean but with a slight wobble. If needed, steam for another 2-3 minutes, checking frequently to avoid overcooking.

Remove the cups from the steamer and let them rest for 2-3 minutes. This helps the flavors meld together and ensures the custard sets fully.

Garnish each cup with fresh mitsuba leaves for a touch of colour and freshness. Serve the Chawanmushi warm, either as an appetizer or as part of a traditional Japanese meal. Enjoy with a light soy sauce drizzle if desired.