Mushroom & Swiss Recipe

Prep

Clean mushrooms by wiping with a damp paper towel; slice to about 1/4-inch thickness. Thinly slice the onion, mince the garlic, and measure out herbs and condiments. Halve the rolls or slice the bread to make 4 sandwiches.

Caramelize onions

Heat 1 tablespoon butter and 1/2 tablespoon olive oil in a large skillet over medium-low heat. Add the sliced onion and a pinch (about 1/4 tsp) of the salt. Cook, stirring occasionally, until soft and deeply golden brown, 18–22 minutes. If onions begin to stick, add 1–2 tablespoons water to deglaze. Remove onions to a bowl and set aside.

Sauté mushrooms

Increase heat to medium-high and add the remaining 1 tablespoon butter and 1/2 tablespoon olive oil to the same skillet. Add the sliced mushrooms in a single layer (work in two batches if necessary). Sprinkle with 2 1/2 teaspoons salt and 1/2 teaspoon black pepper. Cook without moving for 2–3 minutes to brown, then stir and continue cooking until mushrooms release their liquid and it evaporates, about 6–8 minutes total. Add the minced garlic and thyme and cook 30–60 seconds until fragrant. Stir in the Worcestershire sauce, taste and adjust seasoning with remaining black pepper or salt as desired. Return the caramelized onions to the skillet and mix with the mushrooms; keep warm.

Prepare bread and cheese

Spread Dijon mustard on the bottom half of each roll and mayonnaise on the top half. Lay 2 ounces (about 2–3 slices) of Swiss cheese on the bottom half of each roll so the cheese will melt into the mushrooms. If you prefer extra melty cheese, layer half the cheese on the bread and save the rest to top the mushrooms.

Assemble & melt

Divide the warm mushroom-and-onion mixture evenly among the four sandwiches, piling it on top of the cheese. Top with remaining cheese slices if using. Close sandwiches and place them, cheese-side up, on a baking sheet. Broil on high 3–5 inches from the element for 2–3 minutes until the cheese melts and bubbles (watch closely to avoid burning). Alternatively, place sandwiches in a preheated 375°F (190°C) oven for 6–8 minutes or use a covered skillet over low heat with a weight on top to press and melt cheese for 3–5 minutes.

Toast exterior

While cheese is melting, spread softened butter on the outside cut faces of each roll. After broiling or oven melting, heat a skillet over medium heat and toast the buttered exterior until golden and crisp, about 1–2 minutes per side, pressing gently with a spatula.

Finish & serve

If desired, brush the inside of the top roll lightly with 1/4 teaspoon olive oil for shine. Open the sandwiches, scoop the filling slightly to redistribute melted cheese, close and slice in half. Serve hot.