Begin by boiling a large pot of salted water. Once boiling, add the egg noodles and cook according to package directions until al dente, about 6-8 minutes. Drain the noodles well and set aside.

In a large skillet over medium heat, melt 3 tablespoons of butter until bubbly. Add the chopped yellow onion and minced garlic, and sauté for about 2-3 minutes until the onion becomes translucent. Stir in the frozen mixed vegetables and sprinkle with dried thyme, salt, and pepper. Cook for an additional 5 minutes.

Sprinkle 1/4 cup of all-purpose flour over the sautéed vegetables, stirring to combine thoroughly for about 1 minute. Gradually pour in 2 cups of chicken broth while stirring constantly to avoid lumps. Cook, stirring until the mixture thickens, around 4-5 minutes. Add in 1 cup of heavy cream, stirring until the sauce is rich and velvety.

Reduce heat to low, then add the drained egg noodles and 2 cups of shredded cooked chicken to the skillet. Gently fold everything together until the noodles are well-coated with the creamy sauce. Taste and adjust seasoning with additional salt and pepper as needed.

If desired, chop some fresh parsley for garnish and sprinkle it over the top of the pasta before serving.