Mushroom and Onion Quesadillas with Melted Cheese

Quick Recipe Version (TL;DR)

• Yield: 2 quesadillas (2 servings)
• Prep Time: 10 minutes
• Cook Time: 15 minutes
• Total Time: 25 minutes

Quick Ingredients

• 2 (8-inch) soft flour tortillas
• 1 cup (70 g) sliced mushrooms (cremini, button, or mixed)
• 1/2 medium yellow onion, thinly sliced (about 1/2 cup)
• 1 cup (100 g) shredded cheese (mozzarella, Monterey Jack, or cheddar)
• 1 tbsp unsalted butter
• 1 tsp olive oil (or any neutral oil)
• 1 small garlic clove, minced
• 1/4 tsp kosher salt, plus more to taste
• 1/8 tsp freshly ground black pepper
• Pinch of dried thyme or oregano (optional)

Do This

• 1) Heat a 10-inch skillet over medium-high heat for 1–2 minutes.
• 2) Add butter and oil; when foaming, add onions and mushrooms. Sauté 8–10 minutes until deeply golden and soft.
• 3) Stir in garlic, salt, pepper, and herbs (if using). Cook 30–60 seconds, then transfer mixture to a plate.
• 4) Wipe out the skillet lightly. Place 1 tortilla in the dry skillet over medium heat. Sprinkle half the cheese over half the tortilla.
• 5) Spoon half the mushroom-onion mixture over the cheese, top with a bit more cheese, and fold tortilla in half.
• 6) Cook 2–3 minutes per side until the tortilla is golden-brown and cheese is fully melted. Repeat with remaining ingredients.
• 7) Rest 1 minute, slice into wedges, season lightly with salt, and serve hot.

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Why You’ll Love This Recipe

• Big, savory umami flavor from golden sautéed mushrooms and sweet onions.
• Ready in about 25 minutes using just one skillet and simple ingredients.
• Melty, stretchy cheese and crisp-edged tortillas make it incredibly comforting.
• Easy to customize with different cheeses, herbs, or add-ins you already have.

Grocery List

• Produce: Mushrooms, yellow onion, garlic (optional fresh cilantro and lime for serving)
• Dairy: Shredded cheese (mozzarella, Monterey Jack, cheddar, or a blend), unsalted butter, sour cream (optional, for dipping)
• Pantry: Flour tortillas, olive oil, kosher salt, black pepper, dried thyme or oregano (optional), hot sauce or salsa (optional for serving)

Full Ingredients

For the Mushroom & Onion Quesadillas

• 2 (8-inch) soft flour tortillas
• 1 cup (70 g) sliced mushrooms (cremini or white button; about 4–5 medium mushrooms)
• 1/2 medium yellow onion, thinly sliced (about 1/2 cup, 60 g)
• 1 cup (100 g) shredded cheese, loosely packed
  • Recommended: 1/2 cup (50 g) low-moisture mozzarella + 1/2 cup (50 g) Monterey Jack or mild cheddar
• 1 tbsp unsalted butter
• 1 tsp olive oil (or other neutral cooking oil)
• 1 small garlic clove, minced (about 1/2 tsp)
• 1/4 tsp kosher salt, plus a pinch more to finish
• 1/8 tsp freshly ground black pepper (about 2–3 grinds)
• Pinch (about 1/8 tsp) dried thyme or oregano (optional but nice for extra savoriness)

Optional Toppings & Dipping Sauces

• 2–4 tbsp sour cream
• 2–4 tbsp salsa or pico de gallo
• Hot sauce, to taste
• Fresh cilantro leaves, roughly chopped (about 1 tbsp)
• 1 lime, cut into wedges

Step-by-Step Instructions

Step 1: Prep the vegetables and cheese

Rinse the mushrooms briefly under cool water if they are visibly dirty, then pat them very dry with a clean towel or paper towels. Slice them about 1/4 inch (0.5 cm) thick so they brown nicely without disappearing into the filling. Peel the onion and slice it thinly from root to tip into half-moons, about 1/8–1/4 inch thick. Mince the garlic finely. Shred your cheese if it is not already shredded; freshly shredded cheese melts more smoothly than pre-shredded. Set everything within arm’s reach of the stove so cooking goes quickly.

Step 2: Sauté the mushrooms and onions

Place a 10-inch (25 cm) nonstick or well-seasoned cast iron skillet over medium-high heat. Allow it to preheat for 1–2 minutes. Add the butter and olive oil. When the butter is melted and foaming but not browned, add the sliced onions and mushrooms in an even layer. Spread them out so they have contact with the pan. Let them cook undisturbed for 2–3 minutes to start browning, then stir. Continue to cook, stirring every 1–2 minutes, for another 6–7 minutes, until the onions are soft and turning golden and the mushrooms are deeply browned and have released and reabsorbed most of their moisture.

Step 3: Season the filling

Reduce the heat slightly to medium. Add the minced garlic, 1/4 teaspoon kosher salt, 1/8 teaspoon black pepper, and a pinch of dried thyme or oregano if using. Stir constantly for 30–60 seconds, just until the garlic smells fragrant and loses its raw edge; do not let it brown. Taste a small piece and adjust with an extra pinch of salt or pepper if needed. Transfer the mushroom-onion mixture to a plate or bowl and spread it out slightly so it cools for a minute. This brief rest helps keep the tortillas from getting soggy.

Step 4: Warm the tortilla and build the first quesadilla

Wipe out the skillet lightly with a folded paper towel if there are any burnt bits, but leave a very thin film of fat if present. Place the skillet back over medium heat (roughly equivalent to about 350–375°F / 175–190°C surface temperature on an electric griddle). Lay one flour tortilla flat in the dry pan. Warm it for about 30 seconds, then sprinkle about 1/4 cup (25 g) of cheese evenly over half of the tortilla. Spoon half of the mushroom-onion mixture on top of the cheese, spreading it to the edges. Add another 1/4 cup (25 g) of cheese over the vegetables; the cheese on both sides will help the quesadilla hold together.

Step 5: Fold, toast, and melt

Using a spatula, fold the empty half of the tortilla over the filling to form a half-moon shape. Press down lightly with the spatula to help everything stick together. Cook for 2–3 minutes, until the bottom is golden-brown with light, crisp spots. Carefully flip the quesadilla and cook the second side for another 2–3 minutes. Adjust the heat as needed: if the tortilla is browning too quickly before the cheese melts, lower the heat slightly; if it looks pale after 2 minutes, increase the heat a bit. When both sides are golden and the cheese feels melty and soft when you press the top, transfer the quesadilla to a cutting board.

Step 6: Repeat, slice, and serve

Repeat the assembling and cooking process with the second tortilla and remaining cheese and mushroom-onion filling. Let each cooked quesadilla rest on the cutting board for about 1 minute so the cheese can set slightly; this makes slicing cleaner. Use a sharp knife or pizza cutter to cut each quesadilla into 3–4 wedges. Sprinkle with a tiny pinch of salt over the hot tortilla for extra flavor. Serve immediately with sour cream, salsa, hot sauce, cilantro, and lime wedges on the side, if desired.

Pro Tips

• Dry mushrooms = better browning. Pat mushrooms very dry before cooking. Excess moisture will steam them instead of giving you that deep, savory color and flavor.
• Do not overcrowd the pan. If your skillet is small, cook the mushrooms and onions in two batches so they can brown properly.
• Use a cheese blend. Combining a great melter (mozzarella or Monterey Jack) with a flavorful cheese (cheddar) gives you both stretch and taste.
• Control the heat. Medium to medium-high heat is ideal. Too hot and the tortilla burns before the cheese melts; too low and it dries out without crisping.
• Cut after resting. Let the quesadilla sit for 1 minute before slicing to prevent the hot cheese from running out.

Variations

• Garlic-herb mushroom quesadilla: Add an extra clove of garlic and a larger pinch of dried thyme and oregano, then finish the filling with a squeeze of lemon instead of lime.
• Spicy chipotle version: Stir 1–2 teaspoons of chopped chipotle in adobo or a pinch of red pepper flakes into the mushroom-onion mixture in Step 3 for a smoky kick.
• Greens-loaded: In Step 3, stir in 1–2 cups fresh baby spinach and cook just until wilted before assembling the quesadillas.

Storage & Make-Ahead

For best texture, these quesadillas are meant to be eaten right after cooking, while the tortilla is crisp and the cheese is still melty. However, you can make the mushroom-onion filling up to 3 days in advance: cool it completely, then store it in an airtight container in the refrigerator. When ready to eat, rewarm the filling in a skillet over medium heat for 2–3 minutes, then assemble and cook the quesadillas fresh.

If you have leftover cooked quesadillas, let them cool completely, then wrap tightly in foil or store in an airtight container in the refrigerator for up to 2 days. Reheat in a dry skillet over medium heat for 3–4 minutes per side, or in a 375°F (190°C) oven for about 8–10 minutes, until warmed through and crisp again. Avoid microwaving if possible, as it can make the tortillas rubbery.

Nutrition (per serving)

Approximate values per serving (1 quesadilla, without toppings): 460 calories; 24 g carbohydrates; 16 g protein; 32 g fat; 16 g saturated fat; 55 mg cholesterol; 3 g fiber; 4 g sugar; 650 mg sodium. Actual values will vary based on the specific tortillas, cheese, and add-ons you use.