Bring 14 cups of water to a boil in a large pot. Add the leek tops (the dark green parts you'll discard), 10 sprigs thyme, 5 lightly crushed garlic cloves, 1 tablespoon salt, and 1 tablespoon peppercorns. Simmer this mixture for 30 minutes to extract maximum flavor from the leek greens and aromatics. Strain through a fine sieve and measure out 6 cups of the broth, discarding the solids. This concentrated broth becomes the foundation of your soup's flavor.

While the broth simmers, peel the potatoes and cut them into 1-inch chunks—uniform sizing ensures even cooking. For the leeks, trim the dark green tops and white root ends, then slice the white and light green parts into thin half-moons. Place the sliced leeks in a bowl of cold water and swish them around to remove any hidden soil, then drain well. Mince the 4 fresh garlic cloves. I find prepping vegetables while the broth cooks maximizes efficiency without any wasted time.

Melt 3.5 tablespoons of butter in a large pot over medium heat. Add the cleaned, sliced leeks along with a pinch of salt and black pepper, and cook for 8-10 minutes, stirring occasionally, until the leeks become soft and lightly caramelized. This gentle cooking sweetens the leeks and removes their raw bite, creating a more delicate flavor base. The butter helps carry and develop the leek's natural sweetness.

Add the prepared potatoes from Step 2 to the sautéed leeks, followed by the minced fresh garlic, the 6 cups of homemade leek broth from Step 1, and 4 sprigs of fresh thyme and 1 bay leaf. Bring the mixture to a simmer over medium-high heat, then reduce to medium-low and simmer for 20 minutes until the potatoes are completely tender and easily break apart with a fork. The longer, gentle simmer allows flavors to meld while the potatoes soften properly for blending.

Remove the thyme sprigs and bay leaf from the pot. Using an immersion blender, blend the soup until smooth and creamy—blend for about 1-2 minutes, working in batches if needed. I like to leave just a hint of texture rather than making it completely silky, which gives better mouthfeel. Stir in 1 cup of cream and 1 tablespoon of lemon juice, then taste and adjust seasoning with additional salt and black pepper as needed. The lemon juice brightens the richness and adds a subtle complexity.

Ladle the hot soup into bowls and top each serving with finely chopped fresh chives (cut into 1/8-inch pieces for delicate flavor). The bright, fresh chives provide a sharp contrast to the creamy, mild soup and add a pop of color and onion-like flavor that rounds out the dish perfectly.