Bring a large pot of salted water to a boil over high heat. Add egg noodles and cook according to package instructions (7-9 minutes) until al dente. Drain and set aside.

In a large skillet, melt butter over medium heat. Add mixed vegetables and cook for about 5 minutes until tender and bright in color.

Sprinkle flour over sautéed vegetables, stirring continuously for about 1 minute to thicken the sauce.

Gradually pour in chicken broth and heavy cream while whisking. Continue whisking until the sauce thickens and is smooth (3-4 minutes).

Stir in garlic powder, diced cooked chicken, drained egg noodles, and cheddar cheese. Mix gently and warm through for 2-3 minutes.

If using, fold in spinach and cook until just wilted (about 2 minutes). Season with salt and pepper to taste.

Remove from heat and serve immediately in warm bowls, enjoying the comforting aroma and texture.