Combine Ingredients in Crockpot: In a 4-6 quart crockpot, add 3 cups of chicken broth, frozen pierogies, sliced kielbasa, and 1 cup of shredded cheddar cheese. Stir to evenly distribute the ingredients.

Cook the Casserole: Set the crockpot to cook on high for 3-4 hours or on low for 6 hours. This slow cooking process allows the flavors to develop fully.

Prepare Cream Cheese Mixture: About 30 minutes before the end of the cooking time, warm the cream cheese with the remaining 1 cup of chicken broth. You can do this in the microwave or on the stovetop. Whisk the mixture until smooth.

Final Assembly: Pour the cream cheese mixture into the crockpot and stir well to combine. Sprinkle additional shredded cheddar cheese over the top. Cover and cook on low for an additional 30 minutes to allow the cheese to melt and the flavors to blend.

Serve: Serve the casserole hot, optionally garnished with sliced green onions for added color and a mild onion flavor.