Special equipment: six 12-ounce ramekins
Preheat the oven to 350 degrees F. Grease six 12-ounce ramekins with 2 tablespoons of the butter and set aside on a rimmed baking sheet.
Spread the brioche on a second rimmed baking sheet and bake, tossing halfway through, until lightly browned, about 15 minutes.
Melt the remaining 2 tablespoons butter in a large skillet over medium-high heat. Add the sausage and squash and cook, breaking up the meat with the back of a spoon, until the sausage is browned and the squash is tender, about 8 minutes. Stir in the leeks, thyme, 1 teaspoon salt and 1/2 teaspoon pepper and continue to cook, stirring often, until the leeks are wilted and softened, about 5 minutes.
Whisk together the chicken broth, cream, parsley, chives and eggs in a medium bowl. Add half the brioche to the ramekins. Divide the sausage mixture among the ramekins; top with 1 cup of the Gruyere and the remaining brioche. Pour the egg mixture over and sprinkle with the remaining 1 cup Gruyere.
Set aside at room temperature for 15 minutes to allow the bread to absorb the egg mixture. Bake on the baking sheet until the custard is set and the bread pudding is puffed and golden, about 20 minutes. Sprinkle with chives before serving.
Copyright 2017 Television Food Network, G.P. All rights reserved.