If using fresh corn, cut kernels from the cobs and reserve 1 tablespoon of kernels for garnish. Measure 4 cups of kernels total. Finely chop onion, carrot, and celery; mince garlic; gather thyme and bay leaf.

Sweat aromatics

In a large heavy saucepan or medium stockpot, melt the butter over medium heat. Add the chopped onion, carrot, and celery and a pinch of salt. Cook, stirring occasionally, until the vegetables are softened and the onion is translucent, about 6–8 minutes. Add the minced garlic and cook 30–45 seconds until fragrant.

Add corn and cook briefly

Add 3 3/4 cups of the corn kernels to the pot (reserve the remainder for garnish). Stir to combine and cook 2–3 minutes to warm the corn and bring out sweetness.

Make a light roux

Sprinkle the flour over the vegetables and corn, stirring constantly for 1–2 minutes to cook the raw flour taste and coat the mixture. This will slightly thicken the soup.

Add liquid and herbs

Slowly pour in the broth while stirring to avoid lumps. Add the bay leaf and thyme. Increase heat to bring the mixture to a gentle simmer, then reduce heat to medium-low and simmer uncovered for 12–15 minutes so flavors meld and corn softens further.

Purée part of the soup (texture control)

Remove and discard the thyme stems and bay leaf. For a creamy yet textured soup, transfer about half to two-thirds of the soup to a blender in batches (or use an immersion blender in the pot) and purée until smooth. Return puréed soup to the pot and stir to combine. If you prefer an entirely smooth soup, purée all of it.

Add milk and adjust

Stir in the milk (or half-and-half) and heat gently over low heat until warmed through. Do not boil after adding milk to prevent curdling. Taste and season with salt and freshly ground black pepper; adjust to preference.

Finish & Serve

Finish with cream and lemon (optional)

If using, stir in the heavy cream for extra richness and the lemon juice to brighten flavor. Warm gently for 1 minute, then remove from heat.

Garnish and serve

Ladle the soup into bowls. Sprinkle reserved corn kernels over each bowl (you can quickly sauté these reserved kernels in a small pan with a bit of butter until slightly charred for extra texture), then scatter chopped chives or parsley and a crack of black pepper. Serve hot.

Storage

Cool to room temperature, then refrigerate leftover soup in an airtight container for up to 3–4 days. Reheat gently on the stovetop, adding a splash of broth or milk if the soup has thickened.