Finely slice the shallots or onions and add them to a large skillet with oil over low heat. Sprinkle in sugar and salt, and cook for 15-20 minutes until caramelized.

In a pot of boiling water, blanch the broccoli florets for 2-3 minutes until bright green and tender-crisp, then drain and run under cold water.

In a large mixing bowl, combine the sautéed onions, blanched broccoli, cheddar, and Gruyère cheese with vegetable or beef broth, salt, and black pepper. Stir until well blended.

Preheat your oven to 350°F (175°C). Grease a baking dish and transfer the broccoli-cheese mixture into it, spreading evenly.

Sprinkle fried onions or Panko breadcrumbs mixed with melted butter over the top before baking.

Bake in the preheated oven for 30-40 minutes, or until the cheese is bubbling and the top is golden brown.