Melt the 2 tablespoons unsalted butter in a large skillet over medium-high heat, add the 1 cup diced onion, and cook until the onion is tender, about 3-4 minutes.
Add the 1 pound chicken breast, to the pan with the 2 teaspoons chicken bouillon powder, 1 teaspoon garlic powder, and ½ teaspoon paprika. Cook the chicken, stirring frequently until it is seared on all sides and mostly cooked through, about 8-10 minutes.
Add in the 12 ounces frozen mixed vegetables and cook until the vegetables are thawed, then pour in the 2 (10.5-ounce) cans cream of chicken soup, 1 cup whole milk, and Salt and pepper to taste. Reduce the heat to low and simmer the sauce for about 8-10 minutes, the chicken should finish cooking.
Cook the 8 ounces wide egg noodles according to the package directions while the sauce is being made. Once the sauce is finished and the chicken is cooked, add the noodles to the pan and toss to coat.