In a large heavy-bottomed pot, melt the butter over medium heat until foaming. Add the diced onion, celery and carrot. Cook, stirring occasionally, until the vegetables are softened and the onions are translucent, about 6–8 minutes.

add garlic and flour

Add the minced garlic and cook for 30 seconds until fragrant. Sprinkle the flour over the vegetables and stir constantly for 1–2 minutes to remove the raw flour taste and form a light roux.

deglaze and simmer

Slowly whisk in 1 cup of the stock to loosen the roux, scraping any browned bits from the bottom. Once smooth, pour in the remaining stock, then add the bay leaf and thyme. Bring the mixture to a gentle simmer.

add milk

Stir in the milk, reduce heat to medium-low, and maintain a gentle simmer (do not boil vigorously to avoid curdling) while you add the main add-ins in the next steps.

Main Add-ins

cook potatoes

Add the cubed potatoes to the simmering soup base. Simmer uncovered until the potatoes are tender when pierced with a fork, about 12–15 minutes depending on cube size.

add protein and peas

If using shredded cooked chicken, stir it into the pot to warm through, about 3–4 minutes. Add the frozen peas and continue to cook 2–3 minutes until peas are heated. Taste for doneness and adjust texture; if soup is too thick, add up to 1/2 cup extra stock or water and stir to combine.

Seasoning & Finish

season and finish

Remove and discard the bay leaf and thyme sprigs. Season the soup with the salt and freshly ground black pepper, then stir in the chopped parsley and optional lemon juice. Let sit off heat for 2 minutes so flavors meld.

serve

Ladle the soup into bowls and finish with an extra sprinkle of parsley and a grind of black pepper. Serve hot with crusty bread if desired.