Our neighbor always brought a batch to summer block parties. Only 4 ingredients for a warm, comforting treat that tastes better than takeout.

These Low Carb 4-Ingredient Parmesan Mushroom Bakes are my tribute to our old neighbor who *always* showed up to the summer block party with a hot casserole dish of cheesy mushrooms. They’d disappear before the burgers were even off the grill. This version keeps her spirit of “simple but impressive” alive: just four everyday ingredients, minimal prep, and a cozy, takeout-level flavor that feels way fancier than the effort it takes. They’re perfect for busy weeknights, potlucks, or whenever you need a warm, comforting bite without turning your whole kitchen upside down.

Serve these Parmesan mushroom bakes straight from the casserole dish while they’re still sizzling and golden. They’re great as a low-carb side next to grilled chicken, steak, or baked salmon, or as a hearty appetizer with toothpicks. I like to pair them with a crisp green salad or roasted veggies to round out the plate. For a more casual feel, set the dish in the middle of the table with small plates and let everyone help themselves, just like at a block party.

Servings: 4

1 1/2 pounds whole cremini or button mushrooms, stems removed

Preheat your oven to 400°F (200°C). Lightly grease a medium ceramic casserole dish with a thin film of olive oil so the mushrooms don’t stick.

Clean the mushrooms by wiping them with a damp paper towel. Gently twist and pull out the stems so you have little caps with room to hold cheese. Pat the caps dry so they roast instead of steam.

In a large bowl, add the mushroom caps. Drizzle with 3 tablespoons olive oil and sprinkle with the garlic powder and 1/2 cup of the grated Parmesan. Toss well until every mushroom is lightly coated and the cheese clings to the caps.

Arrange the mushrooms in a single snug layer in the prepared casserole dish, open side up. Make sure they’re fairly close together so they help support each other as the cheese melts.

Evenly sprinkle the remaining 1 cup Parmesan over the tops of the mushrooms, filling the cavities and covering the caps so you’ll get a bubbly, golden layer when baked.

Bake on the middle rack for 18–22 minutes, or until the mushrooms are tender and the Parmesan is melted, bubbling, and turning golden brown around the edges. If you want deeper browning, broil for 1–2 extra minutes, watching closely so the cheese doesn’t burn.

Let the casserole rest for 5 minutes before serving so the cheese can set slightly and the mushrooms aren’t lava-hot. Serve warm right from the baking dish.

To change things up while keeping the low-carb, four-ingredient spirit, you can swap the garlic powder for onion powder or Italian seasoning for a different flavor profile. Use a blend of Parmesan and another hard cheese like Asiago or Romano (counted together as your cheese ingredient) for a sharper, more complex taste. If you’re dairy-sensitive, look for a lactose-free aged Parmesan-style cheese. For a little heat, add a pinch of red pepper flakes to the olive oil and garlic powder before tossing with the mushrooms (still treated as part of your seasoning ingredient). Meal prep tip: you can clean, stem, and season the mushrooms earlier in the day, then cover and refrigerate in the casserole dish; just add the final layer of cheese right before baking. Food safety notes: always refrigerate mushrooms and any leftovers within 2 hours of baking, and reheat leftovers to at least 165°F (74°C) before eating. Discard any mushrooms that smell off or feel slimy before cooking, and avoid rinsing them under running water right before baking, as excess moisture can cause uneven cooking and steaming instead of roasting.