Food & Cooking Recipes Lunch Recipes Grilled Gruyère Sandwich With Onion Jam This next-level grilled cheese is our favorite. Close Credit: Sidney Bensimon Prep Time: 20 mins Total Time: 25 mins Servings: 4 Jump to recipe Nutty Gruyère cheese is complemented by piquant Dijon mustard and sweet onion jam in this elevated grilled cheese sandwich. Martha's Secret to the Perfect Grilled Cheese Sandwich Directions Make butter-mayo mixture and spread on bread: Arrange bread in a single layer on a clean work surface. Stir together butter and mayonnaise. Spread mixture evenly onto one side of every slice (1 scant tablespoon per slice). Heat skillet; Flip bread and spread Dijon: Heat a large skillet, preferably cast iron, over medium. Flip over bread on work surface (so it's plain-side up). Spread Dijon evenly onto 4 slices. Spread other slices with onion jam: Spread onion jam onto remaining 4 slices and top evenly with cheese. Carefully sandwich together. Cook sandwiches: Place sandwiches in skillet (in two batches, if needed). Reduce heat to medium-low; gently top sandwiches with a lid slightly smaller than skillet for even cooking. Cook, flipping once halfway through, until crisp and golden on both sides and cheese is melted, 7 to 9 minutes. Serve immediately. Cook's Notes Our test kitchen's pick for onion jam is The Jam Stand Sweet Wino Onion Jam, available at amazon.com.