Preheat your oven to 400 degrees F and spray a large baking dish with nonstick spray. Set aside.

Have a large bowl of ice water ready. Bring a large pot of water to a boil. Salt the water, and add the green beans. Cook until they just have a bite, about 5 minutes and then drain. Transfer the green beans immediately to the bowl with the ice water to stop the cooking process, then drain for a second time. Set aside.

Heat a nonstick skillet over medium heat. Add the Johnsonville Ground Italian Sausage to the pan, and cook until just browned and cooked through, about 8 minutes. Remove from pan with a slotted spoon. Discard all but about a tablespoon of the fat, and leave the pan over medium heat.

Melt the 1/4 cup of butter. Add the mushrooms and cook until tender, about 8 minutes. Add the garlic and cook for an additional 1 minute. Whisk in the flour. Cook, stirring frequently, until golden brown and the flour has absorbed a lot of the liquid. Whisk in the vegetable broth and bring to a gentle simmer. Whisk in the whole milk and half and half and season with a generous amount of salt and black pepper to taste. Sprinkle with cayenne pepper if desired, and continue simmering for about 15 minutes or until thickened. Stir the green beans and cooked sausage into the mixture and remove from heat.

While your mushroom sauce is thickening, prepare your bread crumbs. In a small skillet, melt the remaining 2 tablespoons of butter over low heat. Add the panko bread crumbs. Stir them frequently until they start to turn a golden brown. This might take a few minutes, so be patient. Remove from heat.

Pour the green bean/sausage mixture into the prepared pan. Sprinkle with the bread crumbs. Bake the sausage green bean casserole, for 15 minutes or until bubbly. Remove from heat and serve. Enjoy!