Prep Time: 25 minutes
Cook Time: 45 minutes
Total Time: 1 hour 10 minutes
Skill Level: Easy / Medium (Easy for experienced cooks, Medium for beginners due to making a roux-based sauce)
Servings: 6-8 as a main course, 10-12 as a side dish
Cuisine: American Comfort Food
Ingredients
For the Casserole Base:
2 lbs (about 4-5 medium) Russet or Yukon Gold potatoes, scrubbed and cut into ½-inch cubes
1 large head broccoli, cut into small florets
2 large carrots, peeled and diced
1 medium yellow onion, diced
3 tablespoons olive oil, divided
1 teaspoon garlic powder
1 teaspoon smoked paprika
1 teaspoon salt, plus more for the potato water
½ teaspoon black pepper
For the Cheese Sauce:
4 tablespoons (½ stick) unsalted butter
¼ cup all-purpose flour
2 cups whole milk, warmed (room temperature is fine)
1 cup low-sodium vegetable or chicken broth, warmed
3 cups sharp cheddar cheese, freshly grated (about 12 oz), divided
½ cup sour cream
1 teaspoon Dijon mustard
½ teaspoon onion powder
¼ teaspoon cayenne pepper (optional, for a little heat)
Salt and white pepper to taste
For the Topping:
1 cup panko breadcrumbs
2 tablespoons unsalted butter, melted
¼ cup freshly grated Parmesan cheese
2 tablespoons fresh parsley, chopped (for garnish)
Instructions
Phase 1: Prep & Par-Cook (Intensity: Medium)
Preheat & Prep: Preheat your oven to 400°F (200°C) . Lightly grease a 9×13-inch baking dish.
Boil the Potatoes: Place the cubed potatoes in a large pot and cover with cold water by an inch. Add a generous tablespoon of salt. Bring to a boil and cook for 7-9 minutes, until the potatoes are just fork-tender but still firm. They should not be falling apart. Drain well and set aside.
Roast the Vegetables: While the potatoes boil, place the broccoli florets, diced carrots, and diced onion on a large baking sheet. Drizzle with 2 tablespoons of olive oil, and sprinkle with ½ teaspoon salt, ¼ teaspoon pepper, and the garlic powder. Toss to coat. Roast for 12-15 minutes, until the vegetables are crisp-tender and the edges of the broccoli begin to caramelize. Remove from the oven and set aside. Leave the oven on.
Phase 2: The Cheese Sauce (Intensity: Medium/High)
Make the Roux: In a large Dutch oven or heavy-bottomed saucepan, melt 4 tablespoons of butter over medium heat. Once foaming, add the flour and whisk constantly for 1-2 minutes until the mixture is smooth and smells slightly nutty (this cooks out the raw flour taste). Be careful not to let it brown.
Build the Sauce: Slowly pour in the warm milk and warm broth, whisking continuously to prevent lumps. Continue to whisk as the mixture comes to a gentle simmer. Cook for 3-4 minutes, until the sauce thickens enough to coat the back of a spoon.
Add Flavor & Cheese: Reduce the heat to low. Stir in the Dijon mustard, onion powder, and cayenne pepper (if using). Gradually add 2 ½ cups of the sharp cheddar cheese, a handful at a time, stirring until completely melted and smooth. Stir in the sour cream until well combined. Taste the sauce and season with salt and white pepper (white pepper blends in better, but black pepper works too). Remove from heat.
Phase 3: Assemble & Bake (Intensity: Low)
Combine: In the large pot used for the sauce (or a large mixing bowl), combine the drained potatoes, roasted vegetables, and the entire pot of cheese sauce. Gently fold everything together until all the components are evenly coated.
Transfer: Pour the mixture into the prepared 9×13-inch baking dish, spreading it into an even layer.
Top It Off: In a small bowl, combine the panko breadcrumbs, melted butter, and Parmesan cheese. Sprinkle this mixture evenly over the top of the casserole.
Bake: Place the dish in the preheated oven and bake for 20-25 minutes, until the casserole is bubbly around the edges and the breadcrumb topping is golden brown and crispy.
Rest: Remove from the oven and let it rest for 10-15 minutes before serving. This allows the casserole to set, making it easier to serve. Garnish with fresh parsley.
Chef’s Tips & Variations
Make It Ahead: Assemble the casserole completely (up to step 8) but do not add the topping. Cover and refrigerate for up to 24 hours. When ready to bake, add the topping and increase baking time by 10-15 minutes, covering with foil if the top browns too quickly.
Add Protein: This casserole is fantastic with 1 ½ cups of diced cooked ham, shredded rotisserie chicken, or cooked Italian sausage added to the mix before baking.
Vegetable Swaps: Feel free to substitute or add other vegetables like cauliflower, peas, mushrooms, or kale. Just be sure to roast or sauté them first to remove excess moisture.
For a Crispier Top: For the last 5 minutes of baking, switch the oven to the broiler setting. Watch it carefully to prevent burning.
Storage & Reheating
Refrigerator: Store leftovers in an airtight container in the refrigerator for up to 4 days.
Freezer: This casserole freezes beautifully. Bake, cool completely, wrap tightly in foil and plastic wrap, and freeze for up to 3 months. Thaw overnight in the refrigerator before reheating.
Reheating: Reheat individual portions in the microwave. To reheat the whole casserole, cover with foil and warm in a 350°F oven for 15-20 minutes, or until heated through.
Nutrition Information
Note: Nutrition is an estimate and is calculated for 1 serving (based on 8 servings as a main course). Values will vary based on specific ingredients and portion sizes.
Nutrient Amount per Serving
Calories 485 kcal
Total Fat 29 g
Saturated Fat 15 g
Trans Fat 0.5 g
Cholesterol 75 mg
Sodium 720 mg
Total Carbohydrates 38 g
Dietary Fiber 5 g
Sugars 7 g
Protein 18 g
Vitamin A 185% DV
Vitamin C 65% DV
Calcium 380 mg
Iron 2 mg