Heat the oven to 450°F. Peel the rutabaga with a vegetable peeler and cut into ½-inch and ¾-inch cubes.
Melt the butter in a saucepan over medium heat and cook for about 5 minutes, until the butter foams then browns into a nutty, toasty-smelling liquid.
Toss the rutabaga with the browned butter and season with salt and pepper. Transfer the rutabaga to a large baking sheet and spread into a single layer. Roast for 25-40 minutes or until browned and tender. Remove from the baking sheet and toss with lemon juice and parsley.