Cheesy Baked Mushrooms with Onion and Bell Pepper
Golden, juicy mushrooms baked with sautéed onions and colorful bell peppers, then smothered in a rich blend of melted cheeses. This easy casserole-style dish delivers earthy mushroom flavor with sweet pepper crunch and irresistible gooey cheese topping — simple, satisfying, and ready in under an hour for any occasion.
Why You’ll Love This Recipe:
You’ll fall head over heels for this Cheesy Baked Mushrooms with Onion and Bell Pepper because it transforms humble ingredients into something truly special. The mushrooms become tender and meaty while releasing their natural umami juices that mingle beautifully with the sweetness of caramelized onions and the bright, slightly crisp pops of bell pepper.
Then comes the star — a generous blanket of melted cheese that turns bubbly and golden in the oven, creating that crave-worthy stretchy, gooey texture everyone adores. It’s incredibly versatile (serve as a side with steak or chicken, scoop onto toasted bread, or enjoy solo as a low-carb vegetarian delight), uses pantry-friendly ingredients, comes together quickly with minimal hands-on time, and fills your kitchen with the most inviting savory aroma.
Plus, it’s naturally gluten-free (with minor tweaks) and feels indulgent without being heavy — the perfect crowd-pleaser for family dinners, potlucks, or cozy nights in.
Cheesy Baked Mushrooms with Onion and Bell Pepper
Gooey cheesy baked mushrooms with sautéed onion and bell pepper — easy, flavorful, and irresistibly comforting vegetarian dish.
Ingredients
- 1.5 lbs (680g) cremini or button mushrooms, cleaned and thickly sliced (or quartered if large)
- 1 large onion, thinly sliced
- 1 large red bell pepper, diced (or mix of colors)
- 2–3 cloves garlic, minced
- 2 tablespoons olive oil or butter
- 1½ cups shredded sharp cheddar cheese (divided)
- 1 cup shredded mozzarella cheese
- ¼ cup grated Parmesan cheese
- ½ teaspoon dried thyme (or 1 tsp fresh)
- ½ teaspoon paprika (optional, for color and warmth)
- Salt and black pepper to taste
- Fresh parsley, chopped (for garnish, optional)
Instructions
- Get excited and preheat! Turn your oven to 400°F (200°C) so it’s nice and hot, ready to work its magic on this cheesy goodness. Lightly grease a 9×13-inch baking dish (or similar size) with a little oil or butter — this prevents any sticking and makes cleanup a breeze.
- Sauté like a pro. Heat the olive oil or butter in a large skillet over medium heat. Toss in the sliced onion and diced bell pepper. Cook for 5–7 minutes, stirring occasionally, until the onion softens and turns sweetly golden at the edges — your kitchen will smell amazing already!
- Bring in the mushrooms. Add the sliced mushrooms and minced garlic to the pan. Keep cooking for another 6–8 minutes. The mushrooms will release their liquid — let most of it evaporate so the dish stays rich, not soupy. Stir in thyme, paprika (if using), a good pinch of salt, and black pepper. Taste and adjust — this is your flavor foundation!
- Transfer to baking dish. Scoop the beautiful sautéed veggie mixture into your prepared baking dish. Spread it out evenly so every bite gets some love.
- Cheese, glorious cheese! Sprinkle about 1 cup of the cheddar and all the mozzarella evenly over the top. Give it a gentle press so it nestles in. This double-cheese layer guarantees that perfect melty pull.
- Final cheesy crown. Scatter the remaining ½ cup cheddar and the Parmesan all over. That Parmesan will crisp up beautifully and add a nutty edge — pure perfection.
- Into the oven! Bake uncovered for 20–25 minutes. You want the edges bubbling and the cheese turned into a gorgeous golden, slightly crispy topping. If you love extra color, switch to broil for the last 1–2 minutes (keep eyes on it!).
- Rest and admire. Remove from the oven and let it sit for 5 minutes. This little rest lets the juices settle and the cheese firm up just enough for easy serving — patience pays off here!
- Garnish and serve. Sprinkle with fresh chopped parsley if you want that pop of green and freshness. Scoop generous portions onto plates — watch everyone’s faces light up!
- Enjoy every bite! Dig in while it’s warm and gooey. Pair with crusty bread, grilled protein, or a crisp salad. You just made something simple into something unforgettable — high-five!
Notes
This dish is naturally gluten-free (double-check cheese labels). For best texture, don’t skip evaporating mushroom liquid. Adjust cheese amounts to your gooey preference. Great for meal prep — assemble ahead and bake when ready.
Nutrition Information
Yield
6Serving Size
1Amount Per Serving Calories 510Total Fat 38gSaturated Fat 19gUnsaturated Fat 19gCholesterol 97mgSodium 892mgCarbohydrates 16gFiber 3gSugar 5gProtein 31g
The recipes and nutritional information on Yum Tonight are for informational purposes only. Always consult a healthcare provider for personalized dietary advice.
Recipe Tips and Tricks:
- Use large cremini or portobello mushrooms for best texture; smaller button mushrooms work but release more liquid.
- Pat mushrooms dry after cleaning to prevent a watery dish — never soak them.
- Sauté veggies until onions are soft and slightly caramelized for deeper flavor; don’t rush this step.
- For extra golden cheese topping, broil for the last 2 minutes (watch closely to avoid burning).
- Add a sprinkle of panko or crushed crackers before baking if you want a crispy top.
- Taste the filling before baking and adjust salt/pepper — mushrooms soak up seasoning.
- Let it rest 5 minutes after baking so juices settle and cheese sets slightly for cleaner scoops.
Ingredients Notes:
Fresh mushrooms are essential — choose firm, plump cremini (baby bella) or white button mushrooms; they hold shape well during baking and offer a robust earthy taste. Large portobellos can be used for a more substantial, steak-like portion.
Onions (yellow or white) provide sweet aromatic base when sautéed; avoid red onions unless you want sharper bite. Bell peppers bring color, mild sweetness, and gentle crunch — use a mix of red, yellow, or green for visual appeal and flavor layers.
Garlic adds that classic savory depth. For cheese, sharp cheddar delivers bold tang, mozzarella creates perfect melt and stretch, and a touch of Parmesan adds nutty, salty finish. Olive oil or butter helps sautéing and adds richness; seasonings like thyme, salt, pepper, and optional paprika or Italian herbs elevate everything without overpowering the natural vegetable flavors.
Variations and Substitutions:
Make it spicier by adding diced jalapeños, red pepper flakes, or a dash of hot sauce to the veggie sauté. For a meaty twist, mix in cooked bacon bits, crumbled sausage, or diced ham before baking.
Go dairy-free using plant-based cheese shreds and vegan cream cheese or nutritional yeast for umami. Swap half the mushrooms for chopped zucchini or eggplant for extra veggies. Use different cheeses — try gouda for smokiness, fontina for creaminess, or pepper jack for heat. Add spinach or kale in the last minute of sautéing for greens.
For gluten-free, it’s already safe; just check cheese labels. Turn it low-carb/keto by skipping any breadcrumb topping. For a stuffed version, fill large portobello caps instead of slicing everything. Add cooked quinoa or rice for heartier main-dish portions.
Storage Options:
Store leftovers in an airtight container in the refrigerator for up to 3–4 days. Reheat in a 350°F (175°C) oven for 10–15 minutes until warmed through and cheese bubbles again (microwave works but softens texture). Freezing is possible — portion into freezer-safe containers for up to 2 months; thaw overnight in fridge and reheat in oven (note: texture may be slightly softer after freezing).
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