In a large Dutch oven, heat 1 tablespoon of the olive oil over medium heat.
Add the sausages, browning on both sides, approximately 3-4 minutes. Remove to a plate and set aside.
Add the remaining 1 tablespoon of olive oil to the pot. Add the onions, sauteing until they start to soften, approximately 2-3 minutes. Add the garlic, thyme and oregano, cooking for an additional 1 minute.
Deglaze the pan with white wine, scraping up all of the browned bits. Add the chicken broth, Dijon mustard, navy beans with liquid, drained tomatoes and salt. Bring to a low simmer and then add the sausages back to the pot. Turn the heat off.
Prepare the topping by stirring together the bread crumbs, parmesan cheese, salt and pepper.
Evenly sprinkle the topping over the top of the cassoulet. Bake in the preheated oven for 18-20 minutes, or until breadcrumbs are lightly browned.
Remove and allow to rest for 5 minutes before serving over rice or with crusty bread.
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