In a large pot, melt the unsalted butter over medium heat.
Add the minced garlic and ginger and sauté for 1-2 minutes until fragrant.
Pour in the chicken broth and water, then stir in the soy sauce and miso paste until the miso is fully dissolved.
Bring the broth to a gentle boil.
Add the dried ramen noodles to the pot and cook for 3 minutes.
Add the sliced shiitake mushrooms, shredded carrots, and baby spinach leaves to the pot.
Continue cooking for another 3-4 minutes until the noodles are tender and the vegetables are softened.
Reduce the heat to low and stir in the heavy cream, sesame oil, and black pepper.
In a separate small pot, bring water to a boil and carefully add the large egg.
Boil the egg for 7 minutes for a soft-boiled center.
Remove the egg from the boiling water and place it in an ice bath for 2 minutes, then peel and slice in half.
Ladle the creamy ramen into bowls, top each with sliced green onions and the halved soft-boiled egg.
Serve immediately.