Preheat the oven to 350°F (175°C) and grease a 9x13 baking dish with butter or cooking spray.

In a large pot, boil water and add egg noodles. Cook for about 6 minutes, then drain and set aside.

Melt 2 tablespoons of butter in a skillet over medium heat, add chopped onions, and sauté for 5-7 minutes until soft and golden brown.

Stir the rinsed and drained sauerkraut into the skillet with the onions and cook for another 3-4 minutes.

In a large mixing bowl, combine the noodles and sauerkraut mixture. Add chicken or vegetable broth and stir until well-coated.

Stir in sour cream or cream cheese until evenly distributed throughout the mixture.

Pour the combined mixture into the prepared baking dish and top with shredded cheese if desired.

Bake for 25-30 minutes until the top is golden and bubbling, then let it rest for 10 minutes before serving.