In a large pot, heat the olive oil over medium heat. Add the chopped onion and sauté until translucent, about 5 minutes.
Stir in the minced garlic and sauté for another minute until fragrant.
Add the diced potatoes to the pot, stirring well to combine with the onions and garlic.
Pour in the vegetable broth and add the dried marjoram. Bring the mixture to a boil, then reduce the heat to low and let it simmer for 20-25 minutes, or until the potatoes are tender.
Once the potatoes are cooked, use an immersion blender to puree the soup until smooth. If you prefer a chunkier texture, blend only half of the soup and mix it back in.
Stir in the heavy cream and season with salt and pepper to taste. Let it simmer for an additional 5 minutes to heat through.
Serve hot, garnished with fresh dill or chives for a burst of color and flavor.
Notes
For a chunkier texture, blend only half of the soup.