In a large Dutch oven over medium heat, melt the butter until bubbly. Add the diced yellow onion and sauté for about 5 minutes until translucent and slightly softened.

Stir in the minced garlic and cook for an additional minute. Sprinkle in dried rosemary, thyme, and oregano, mixing thoroughly.

Add the chopped zucchini to the pot, cooking for another 5 minutes until softened.

Introduce diced russet potatoes, chicken broth, and soy sauce. Bring to a gentle boil, then reduce heat and simmer for 15-20 minutes until tender.

Blend the mixture using an immersion blender until smooth. Adjust texture as desired.

Return to low heat and stir in the heavy cream and shredded cheddar cheese until melted.

Ladle the soup into bowls, garnishing with fresh herbs or extra cheese if desired.