Recipes Ingredients Meat & Poultry Pork Recipes Rustic Croque Monsieur 3.1 (45) 3 Reviews By Martha Stewart Test Kitchen Martha Stewart Test Kitchen The recipes developed by our test kitchen team have undergone a rigorous process of development and testing, ensuring that every element is optimal, from ingredient amounts to method and cooking time. This process includes triple-testing recipes to ensure they meet our high standards. The many stellar cooks and food editors who have been part of our team include Sarah Carey, Lucinda Scala Quinn, Jennifer Aaronson, Shira Bocar, Anna Kovel, Greg Lofts, Riley Wofford, Lauren Tyrell, and Lindsay Leopold. Editorial Guidelines Updated on July 8, 2019 Print Rate It Share Share Tweet Pin Email Prep Time: 5 mins Total Time: 35 mins Yield: 4 Parmesan cheese helps gives this French sandwich its salty flavor. Ingredients 2 tablespoons unsalted butter, plus more for bread 2 tablespoons all-purpose flour 2 cups whole milk ½ cup grated Gruyere cheese, plus 8 slices ½ cup grated Parmesan cheese 8 thick slices rustic bread 12 slices ham Dijon mustard, for bread Directions Melt butter in a saucepan over medium heat. Whisk in flour. Add milk; bring to a simmer. Cook, whisking frequently, until sauce thickens, about 5 minutes. Remove from heat. Add grated cheeses. Whisk until melted and smooth. Butter bread. Arrange half the slices, buttered side down, on a rimmed baking sheet. Top each with 2 slices Gruyere and 3 slices ham. Spread mustard onto unbuttered sides of remaining bread. Place on top of ham, buttered side up. Preheat broiler. Heat a grill pan or skillet over medium heat. Cook each sandwich until golden brown and cheese melts, about 5 minutes per side. Return to baking sheet. Spoon 1/3 cup sauce over top of each sandwich. Broil until tops are bubbling and golden brown, about 3 minutes. Rate it Print