1-In a Dutch oven, melt the 4: In a Dutch oven, melt the 4 tablespoons of butter over medium heat. Add the sliced red onions and stir to coat. Sprinkle with the teaspoon of sugar. Cook over medium heat, alternating between medium and medium low to prevent the onions from burning. Stir occasionally, you want to give them time to sit on the bottom of the pot to get browned, but stirring enough to prevent burning. Cook for 35 minutes, sprinkle with a bit of salt then spoon into a bowl and set aside.
2-To make the dipping broth, to the: To make the dipping broth, to the same Dutch oven add the 2 tablespoons of butter to begin to deglaze the bottom of the pot. Whisk in the 2 tablespoons of flour, then the thyme, sherry, beef broth, and pepper. Stir to combine then heat over medium heat for 3-5 minutes until it slightly thickens into a dipping consistency. Pour into a bowl and set aside until the grilled cheeses are done.
3-To make the grilled cheeses, butter each: To make the grilled cheeses, butter each side of the hearty bread and add to a pan over medium heat. Once the first side is browned and toasted, flip the bread and to one side add as much cheese and onions as you’d like, then top with the other slice of bread. Continue to toast until the cheese has melted.
4-Slice and serve with a bowl of: Slice and serve with a bowl of the dipping broth.