Start by slicing the white onions and mushrooms into medium-thin pieces, ensuring uniform sizes for even cooking. Clean the mushrooms with a damp cloth to remove any dirt. Gather your ingredients, including your butter and all-purpose seasoning blend, to streamline your cooking process with this delicious caramelized mushrooms and onions recipe.

In a large skillet, melt 2 tablespoons of butter over medium-low heat, allowing it to bubble gently without browning. The melted butter creates a rich base for your caramelized mushrooms and onions.

Once the butter is melted, add the sliced onions and mushrooms into the skillet, ensuring that they are evenly distributed. Sprinkle your seasoning blend over the mixture, stirring gently to coat all pieces.

Let the mixture sauté for about 30 minutes over low heat, stirring occasionally to prevent stuck bits and ensure even caramelization.

Once the mushrooms and onions are beautifully caramelized, remove the skillet from heat. Transfer your savory creation to a serving dish or use it as a versatile topping for burgers, steaks, or even pasta.