Preheat oven to 425° F.
In a large Dutch oven or other heavy pot, melt the butter over medium heat.
4 tablespoons unsalted butter
Add the chopped onion, carrots and celery to the pot. Cook, stirring occasionally, until softened, about 5 minutes.
1 small yellow onion, 3 medium carrots, 3 ribs celery
Stir in the minced garlic and flour and cook, stirring, for 1 minute.
3 cloves garlic, ⅓ cup all-purpose flour
Stir in the broth and milk, followed by the dried thyme, salt and pepper. Cook, stirring often, until the mixture begins to bubble and thickens, about 2 minutes.
1 ¾ cups low sodium chicken broth, ½ cup milk, 1 teaspoon dried thyme, ½ teaspoon salt, ¼ teaspoon black pepper
Remove the pot from the heat and stir in the turkey and frozen peas.
2 cups chopped leftover roast turkey, ½ cup frozen peas