Cheesy Roasted Vegetable Gratin: The Ultimate Low-Carb Comfort Food

If you are looking for a way to make vegetables the star of the show, this Cheesy Roasted Vegetable Gratin is the answer. It is a vibrant, colorful, and deeply satisfying dish that combines the earthiness of roasted broccoli, the sweetness of bursting cherry tomatoes, and the tender bite of zucchini, all brought together by a rich, bubbly cheese sauce. This isn’t just a side dish; it is hearty enough to stand alone as a vegetarian main course or a decadent low-carb dinner.

The magic of this recipe lies in the roasting. By baking the vegetables directly in the creamy cheese mixture, the juices from the tomatoes and zucchini release into the sauce, creating a flavor profile that is savory, bright, and utterly delicious. The “liquid glass” shine of the melted cheese and the charred edges of the broccoli make this dish as beautiful to look at as it is to eat. Whether you are meal prepping for the week or looking for a cozy Sunday night dinner, this gratin delivers on all fronts.

Why You Will Love This Recipe

• Nutrient-Packed: Loaded with fresh broccoli, zucchini, and antioxidant-rich tomatoes.
• Keto & Low Carb Friendly: High in healthy fats and fiber, low in carbs, and completely gluten-free.
• One-Pan Wonder: Everything bakes together in one dish, minimizing cleanup.
• Versatile: It works as a festive holiday side dish or a simple weeknight meal.

Ingredients

For the Vegetables:

• Broccoli Florets – 1 large head, cut into bite-sized pieces. Fresh is best for that crisp-tender texture.
• Zucchini – 1 medium, sliced into rounds (about 1/4 inch thick).
• Cherry Tomatoes – 1 cup, a mix of red and yellow/orange for visual appeal and sweetness.
• Olive Oil – 2 tablespoons, for tossing the vegetables.
• Salt and Black Pepper – To taste.

For the Cheesy Sauce:

• Heavy Cream – 3/4 cup, provides the luxurious, liquid base.
• Mozzarella Cheese – 1 cup, shredded (freshly grated melts best).
• Parmesan Cheese – 1/2 cup, grated, for that salty, savory punch.
• Garlic – 2 cloves, minced or pressed.
• Dried Oregano – 1/2 teaspoon.
• Fresh Thyme – 4-5 sprigs, for garnish and earthy aroma.

Instructions

1. Preheat and Prep: Preheat your oven to 400°F (200°C). Grease a round ceramic baking dish or a 9×9 inch casserole dish with a little butter or oil.
2. Season Vegetables: In a large mixing bowl, toss the broccoli florets and zucchini slices with olive oil, salt, and pepper. Arrange them tightly in the prepared baking dish.
3. Add Tomatoes: Nestle the red and yellow cherry tomatoes into the gaps between the broccoli and zucchini. You want them evenly distributed so every bite gets a pop of sweetness.
4. Make the Sauce Mixture: In a small bowl or jug, whisk together the heavy cream, minced garlic, dried oregano, and half of the Parmesan cheese. Season with a pinch of salt.
5. Pour and Top: Pour the cream mixture evenly over the vegetables. It won’t cover them completely, and that’s okay—it will bubble up as it cooks. Top generously with the shredded Mozzarella and the remaining Parmesan cheese.
6. Bake: Place in the oven and bake for 25–30 minutes. You are looking for the broccoli edges to char slightly, the tomatoes to burst, and the cheese to become golden, bubbly, and glossy.
7. Garnish and Serve: Remove from the oven. Immediately scatter fresh thyme sprigs over the bubbling cheese. Let it sit for 5 minutes before serving to allow the sauce to thicken slightly.

Tips for the Perfect Gratin

Pro Tip: Don’t overcrowd the broccoli. Leaving the top parts of the florets exposed above the sauce allows them to get that delicious roasted char, while the stems cook tenderly in the cream.

• Avoid Watery Gratin: Zucchini releases water when cooked. To prevent a watery sauce, you can lightly salt the zucchini slices and let them sit on a paper towel for 10 minutes before assembling, patting them dry to remove excess moisture.
• Cheese Choices: Feel free to swap Mozzarella for Gruyère or Fontina for a nuttier, deeper flavor profile.
• Add Protein: To make this a complete non-vegetarian meal, you can add cooked shredded chicken or diced ham into the mix before baking.

Serving Suggestions

This Cheesy Roasted Vegetable Gratin pairs beautifully with a simple arugula salad dressed with lemon vinaigrette to cut through the richness. It is also the perfect accompaniment to grilled steak, roasted chicken thighs, or a holiday roast beef. If you aren’t counting carbs, serve it alongside crusty garlic bread to soak up the “liquid glass” cheese sauce pooling at the bottom of the dish.

Storage and Reheating

Refrigerator: Store leftovers in an airtight container for up to 3 days. The flavors often meld and improve the next day.

Reheating: Reheat in the oven at 350°F until warmed through to maintain the crispy edges of the broccoli. Microwaving is faster but may result in softer vegetables.