Preheat your oven to 400°F (200°C). Unroll the thawed pie crust onto a lightly floured surface. Use small cookie cutters (about 1-2 inches) to cut shapes. Place the shapes on a baking sheet and bake for 8-10 minutes, or until golden brown. Set aside.
While the crust bakes, melt 2 tablespoons of butter in a large pot or Dutch oven over medium heat. Add the onion and carrots and cook, stirring occasionally, until they start to soften, about 5 minutes.
Pour in the chicken broth and add the diced sweet potato. Bring the mixture to a boil, then reduce the heat to maintain a simmer. Cover the pot and cook for 15-20 minutes, until the sweet potatoes are tender when pierced with a fork.
In a separate small saucepan, melt the remaining 4 tablespoons of butter over medium heat. Whisk in the flour and cook for 1 minute, whisking constantly, to form a paste (this is a roux).
Gradually whisk the milk into the roux until smooth. Bring the mixture to a simmer, whisking often, until it thickens, about 2-3 minutes. Remove from the heat and stir in the heavy cream, cheddar cheese, poultry seasoning, salt, and pepper until the cheese is melted.
Pour the creamy cheese sauce into the large soup pot with the vegetables. Stir everything together until well combined.
Add the chopped turkey and frozen peas to the soup. Continue to cook on low heat, stirring gently, until the peas are bright green and the turkey is heated through to a safe internal temperature of 165°F (74°C).
Taste the soup and add more salt and pepper if needed. Ladle the soup into bowls and serve hot, garnished with the baked pie crust toppers.