Preheat oven to 350 degrees. Arrange baguette slices on two large rimmed baking sheets; brush both sides with oil.
Bake until golden, 15 to 20 minutes. Let cool on baking sheets.
Meanwhile, heat a saucepan over medium heat. Add olive oil, butter and mushrooms. Sauté for 5-10 minutes or until mushrooms release their moisture and begin to shrink. Continue cooking until most of the liquid has evaporated.
Add minced garlic, Kosher salt, Italian Herbs and Great Northern Beans. Stir and cook over medium heat until mixture is heated through.
To assemble each piece of Crostini, place a spoonful of mushroom bean mixture on top of a slice of toasted bread. Top with shredded baby swiss cheese.
Serve and enjoy!