In an oil coated medium-size baking dish, toss in the beans, marinara sauce, basil leaves and sautéed mushrooms. Mix well so that the marinara sauce coats all the beans and veggies. Bake in the oven for 40 minutes. At 40 mins, take the dish out of the oven and top with the pesto, feta and breadcrumbs. Pop it back into the oven to cook for another 5-10 minutes, or until the breadcrumbs are crispy and the feta is slightly melted. Let cool and serve in bowls when ready! Enjoy!