Preheat the oven to 400F. Lightly oil a 2-1/2 quart baking dish.

Wrap the parsley, thyme, and bay leaf in a cheesecloth bag and tie it with kitchen twine. Set aside.

Heat 2 tablespoons of the oil in a heavy-bottomed saute pan over medium heat. Add the onion, carrots, and celery. Cook, stirring occasionally, until tender, about 10 minutes.

Add the garlic and stir constantly for about 1 minute. Stir in the beans, tomatoes (with juice), wine, salt, pepper, red-pepper flakes, and the bag of herbs. Reduce the heat to medium-low, cover, and cook for 20 minutes.

Meanwhile, pour 1/2 cup water into a medium skillet over medium heat. Cook the frozen sausages, covered, for about 10 minutes, then drain and cut the sausages into 1" chunks. Add 1 tablespoon of oil to the pan and cook the sausages, turning them occasionally, until all sides are lightly browned, about 5 minutes.

Remove the bag of herbs from the beans and discard it. Transfer 1/2 cup of the bean mixture to a blender (or food processor) and puree until smooth, then stir the puree into the remaining beans. Stir in the sausage. Taste and adjust the seasoning, then pour the mixture into the prepared baking dish.

Combine the bread crumbs with the remaining 1 tablespoon of oil in a small bowl. Spread over the top of the beans.

Bake the cassoulet in the preheated over for 20 minutes, or until it is thoroughly heated and the bread crumb topping is lightly browned.

Garnish the servings with parsley sprigs.