1. In a large soup pot over medium heat, melt the butter, swirling the pot occasionally to coat the bottom.

2. Once the butter has melted and begins to foam, add the diced yellow onion. Sauté, stirring frequently, until the onion turns translucent and soft, about 3 minutes.

3. Stir in the minced fresh garlic and cook for about 30 seconds, until fragrant but not browned.

4. Add the peeled, chopped potatoes and cauliflower florets to the pot. Stir to combine and let them warm through for about 30 seconds.

5. Pour in the chicken or vegetable broth. Add the bay leaf, dried thyme, dried parsley, salt, and freshly ground black pepper. Stir well to distribute the seasonings.

6. Increase the heat to bring the soup up to a gentle boil.

7. Once boiling, reduce the heat to maintain a simmer. Cover the pot and cook, stirring occasionally, until the potatoes and cauliflower are fork-tender, about 15–20 minutes.

8. Remove the pot from the heat. Carefully fish out and discard the bay leaf.

9. Using an immersion blender, puree the soup directly in the pot until completely smooth. (Alternatively, transfer the soup in batches to a countertop blender, blend until smooth, and return it to the pot.)

10. If using, stir in the heavy cream to add extra richness and a luscious mouthfeel.

11. Stir in the fresh lemon juice. Taste and adjust the seasoning with additional salt, pepper, or lemon juice if desired.

12. Ladle the soup into bowls and top with your favorite garnishes: chopped chives, scallions, parsley, croutons, or crumbled bacon.