In a large pot or Dutch oven such as Le Creuset, heat the olive oil over medium heat. Add the onions and cook over medium-low heat for 15 minutes, stirring occasionally, until golden brown. Add the garlic and cook for 1 more minute. Stir in the chicken stock, tomatoes, saffron, 1 tablespoon salt and 1 teaspoon pepper. Bring the soup to a boil, then lower the heat and simmer for 15 minutes.
Meanwhile, fill a medium pot with water, add 2 teaspoons salt and bring to a boil. Add the orzo and cook for 7 minutes. (It will finish cooking in the soup.) Drain the orzo and add it to the soup. Stir in the cream, return the soup to a simmer and cook for 10 more minutes, stirring frequently.
Serve hot with Grilled Cheese Croutons scattered on top.
Grilled Cheese Croutons
Heat a panini grill. Place the four slices of bread on a cutting board and brush lightly with the melted butter, being sure to butter the corners. Turn the slices over and pile Gruyere on two of the slices. Place the remaining two slices of bread on top of the Gruyere, buttered sides up.
Grill the sandwiches on the panini grill for about 5 minutes, until nicely browned. Place on a cutting board, allow to rest for 1 minute and cut into 1-inch cubes.