Step 4: Prepare the Creamy Sauce

In a large mixing bowl, combine:

• Cream of mushroom soup
• Sour cream
• Milk
• Half of the cheddar cheese
• Half of the mozzarella cheese

Mix thoroughly until smooth and creamy.

Season lightly with salt and black pepper. Since kielbasa and cheese already contain salt, avoid over-seasoning.

Step 5: Assemble the Casserole

Spread a small amount of sauce on the bottom of the baking dish.

Add half of the frozen pierogi in an even layer.

Top with:

• Half of the cooked kielbasa
• Half of the onions
• Some of the creamy sauce

Repeat the layers with the remaining ingredients.

Finish by sprinkling the remaining cheddar and mozzarella cheese over the top.

Step 6: Bake the Casserole

Cover the dish loosely with foil.

Bake for 30 minutes.

Then remove the foil and continue baking for another 10–15 minutes until:

• The cheese becomes bubbly
• The top turns golden
• The casserole is heated through completely

The edges should look slightly crisp and creamy at the same time.

Step 7: Rest Before Serving

Allow the casserole to rest for about 5 minutes after removing it from the oven.

This helps the sauce thicken slightly and makes serving easier.

Sprinkle chopped parsley on top for freshness and color.

Serving Suggestions

Baked Pierogi & Kielbasa Casserole pairs wonderfully with simple side dishes such as:

• Fresh green salad
• Roasted vegetables
• Steamed broccoli
• Garlic bread
• Pickles or sauerkraut

The rich and creamy casserole balances especially well with crisp or tangy sides.

Storage and Reheating

Refrigerating

Store leftovers in an airtight container in the refrigerator for up to 4 days.

Freezing

This casserole freezes very well. Wrap tightly and freeze for up to 2 months.

Reheating

Reheat individual portions in the microwave or warm the entire casserole in the oven at 350°F until heated through.

Adding a splash of milk before reheating helps keep the sauce creamy.

Helpful Tips for the Best Casserole

• Do not thaw the pierogi before baking unless instructed on the package.
• Use freshly shredded cheese for smoother melting.
• Brown the sausage well for maximum flavor.
• Let the casserole rest before serving to improve texture.
• Add crispy bacon on top for extra crunch.

Final Thoughts

Baked Pierogi & Kielbasa Casserole is the ultimate comfort food combination. Creamy, cheesy, smoky, and filling, it delivers rich flavor in every bite while remaining simple enough for everyday cooking.

Whether served at a family dinner, potluck, or cozy weekend meal, this casserole is guaranteed to become a favorite. The soft pierogi, savory kielbasa, and bubbling cheese create a warm and satisfying dish that people will request again and again.