Melt 1 tablespoon of the butter in a large skillet. Add the panko and cook, stirring, until the panko toasts, about 3 minutes. Transfer to a bowl.

Melt the remaining 2 tablespoons of butter in the same skillet. Add the carrots and the onion. Season with salt and pepper. Cook over medium heat, stirring often, until they start to soften, about 3 minutes. Add the garlic and cook an additional 30 seconds. Add the flour and stir in and cook for 1 more minute. Add the cream and the stock and bring to a boil. Cook over medium heat, stirring often, until the liquid has reduced by half, about 8 minutes.

Add the chicken to the mixture and cook over medium-low heat, stirring occasionally, until the chicken is cooked through, about 8 minutes. Add the peas to the mixture when there are about 3 minutes left in the cooking time.

Meanwhile, bring a large pot of water to a boil. Salt generously, then add the egg noodles and cook until al dente. Drain.

Combine the ragu with the pasta and stir to combine. Taste and season with salt and pepper, if needed.

Serve the pasta topped with the toasted breadcrumbs, and thyme, if desired.