Preheat the oven to 375F
To make the bechamel sauce, add Ontario butter and flour in a medium saucepan over medium heat. Stir until thick and bubbly and slowly whisk in Ontario milk until the mixture is thick. Add salt, pepper and nutmeg and mix
Generously grease a baking dish with melted Ontario butter. Line slices rutabaga and sweet potato alternatively until full
Pour Béchamel sauce over the sweet potatoes and rutabaga. Top with grated Ontario gruyere and bake for 45 minutes or until tender, golden and bubbling.