Wash and peel the russet potatoes, then chop them into bite-sized cubes. Finely dice the onion and mince the garlic.

Gather your ingredients and equipment, including a large pot and an immersion blender or potato masher for later steps.

In a large pot, melt 4 tablespoons of butter over medium heat. Add the chopped onion, cooking until translucent, about 5 minutes.

Stir in the minced garlic and sauté for an additional 1-2 minutes until fragrant.

Add the chopped potatoes to the pot, then pour in enough vegetable broth to cover the potatoes. Bring to a boil, then reduce to a simmer and cover.

Cook for about 20 minutes, until the potatoes are fork-tender.

Blend the soup directly in the pot using an immersion blender until it reaches your desired creamy consistency.

Stir in 1 cup of heavy cream gradually until well combined.

Season with salt, pepper, and thyme. Heat through on low for a few minutes.

Ladle the soup into bowls and garnish with optional toppings like chives or paprika. Serve warm.