Prep Time: 20 minutes
Cook Time: 45 minutes
Total Time: 1 hour 5 minutes

Servings: 6–8

Difficulty: Easy

Ingredients

For the Casserole

• 2 packages (16 ounces/450 g each) frozen potato and cheese pierogi, thawed
• 14 ounces (400 g) smoked kielbasa or smoked sausage, sliced into ¼-inch rounds
• 2 tablespoons butter
• 2 tablespoons olive oil
• 2 large yellow onions, thinly sliced
• 3 garlic cloves, minced
• 2 cups shredded sharp cheddar cheese
• 1 cup shredded mozzarella cheese
• ½ cup grated Parmesan cheese
• 8 ounces (225 g) cream cheese, softened
• 1 cup sour cream
• 1 cup whole milk
• 1 teaspoon Dijon mustard
• 1 teaspoon onion powder
• ½ teaspoon garlic powder
• ½ teaspoon smoked paprika
• ½ teaspoon black pepper
• ½ teaspoon salt (adjust to taste)
• 2 tablespoons chopped fresh chives
• 2 tablespoons chopped fresh parsley

Optional Topping

• ½ cup crispy cooked bacon, crumbled
• Extra shredded cheddar cheese
• Sliced green onions
• Additional sour cream for serving

Equipment

• 9×13-inch baking dish
• Large skillet
• Medium mixing bowl
• Whisk
• Measuring cups and spoons
• Wooden spoon
• Aluminum foil

Instructions

Step 1: Prepare the Oven

Preheat the oven to 375°F (190°C).

Grease a 9×13-inch baking dish with butter or nonstick cooking spray.

Step 2: Caramelize the Onions

Heat the butter and olive oil in a large skillet over medium heat.

Add the sliced onions and cook for 15–20 minutes, stirring occasionally, until soft, golden, and caramelized.

Add the minced garlic during the final minute of cooking and stir until fragrant.

Transfer the onion mixture to a bowl.

Step 3: Brown the Kielbasa

Using the same skillet, add the sliced kielbasa and cook for 4–5 minutes until lightly browned on both sides.

Remove from the heat.

Step 4: Prepare the Cheese Sauce

In a medium bowl, whisk together the softened cream cheese, sour cream, milk, Dijon mustard, onion powder, garlic powder, smoked paprika, salt, and black pepper until smooth.

Stir in 1 cup of the cheddar cheese and half of the mozzarella until well combined.

Step 5: Assemble the Casserole

Spread a thin layer of the cheese sauce over the bottom of the prepared baking dish.

Arrange half of the pierogi in an even layer.

Top with half of the caramelized onions, half of the kielbasa, and one-third of the remaining cheese sauce.

Repeat the layers with the remaining pierogi, onions, kielbasa, and cheese sauce.

Finish by sprinkling the remaining cheddar, mozzarella, and Parmesan evenly over the top.

Step 6: Bake

Cover the baking dish loosely with aluminum foil.

Bake for 30 minutes.

Remove the foil and continue baking for 10–15 minutes, or until the cheese is melted, bubbling, and lightly golden.

Step 7: Garnish and Serve

Allow the casserole to rest for 10 minutes before serving.

Garnish with chopped parsley, chives, crispy bacon (if using), and sliced green onions.

Serve warm with a dollop of sour cream if desired.

Serving Suggestions

Pierogi Casserole pairs wonderfully with:

• Steamed green beans
• Roasted broccoli
• Garlic butter Brussels sprouts
• Mixed green salad
• Buttered peas
• Roasted carrots
• Pickled vegetables
• Crusty bread
• Apple cider
• Sparkling lemonade

Storage

• Refrigerate leftovers in an airtight container for up to 4 days.
• Freeze the fully baked casserole for up to 2 months.
• Thaw overnight in the refrigerator before reheating.
• Reheat covered in a 350°F (175°C) oven for 20–25 minutes, or microwave individual portions until heated through.

Tips for Success

• Caramelize the onions slowly for the sweetest, richest flavor.
• Thaw the pierogi before assembling to ensure even cooking.
• Smoked cheddar or Gruyère can be substituted for extra depth of flavor.
• Add sautéed mushrooms or spinach for additional vegetables.
• Sprinkle buttered breadcrumbs over the top before baking for a crispy finish.
• Let the casserole rest before serving so it slices cleanly.
• For a vegetarian version, omit the kielbasa and add sautéed mushrooms, spinach, or roasted peppers.

Nutrition Information (Per Serving, Approximate)

• Calories: 590
• Protein: 28 g
• Carbohydrates: 38 g
• Fat: 37 g
• Saturated Fat: 18 g
• Cholesterol: 95 mg
• Fiber: 3 g
• Sugar: 5 g
• Sodium: 980 mg
• Calcium: 30% Daily Value

Frequently Asked Questions

Can I use homemade pierogi?

Yes. Homemade potato and cheese pierogi work beautifully in this casserole. Boil them until just tender before assembling.

Can I make this casserole ahead of time?

Absolutely. Assemble the casserole up to 24 hours in advance, cover tightly, and refrigerate. Bake just before serving, adding 5–10 minutes to the baking time if starting from cold.

Can I make it vegetarian?

Yes. Simply omit the kielbasa and replace it with sautéed mushrooms, spinach, roasted bell peppers, or broccoli for a hearty meat-free version.

What cheeses work best?

Sharp cheddar provides bold flavor, while mozzarella adds a gooey, melty texture. Gruyère, Monterey Jack, or smoked Gouda also make excellent additions.

Can I freeze leftovers?

Yes. Cool the casserole completely, wrap it tightly, and freeze for up to 2 months. Thaw overnight in the refrigerator before reheating.

Recipe Summary

This Pierogi Casserole transforms classic potato and cheese pierogi into a rich, comforting baked meal layered with caramelized onions, smoky kielbasa, creamy cheese sauce, and a golden topping of melted cheddar, mozzarella, and Parmesan. Ready in just over an hour, it’s the perfect make-ahead dinner for busy weeknights, potlucks, and family gatherings. Rich, hearty, and packed with comforting flavors, this easy casserole is sure to become a favorite at the dinner table.