Directions

1. Preheat oven to 350F. Grease a 9 by 13 inch baking dish with butter.  Set aside.
2. Bring a large pot of salted water to a boil. Add the pasta and cook for about 10 minutes. Drain, return to pot, and toss with olive oil. Set aside.
3. While the pasta is cooking make the cheese sauce. Melt the butter in a saucepan over medium-low heat. Whisk in the flour and cook, whisking often, until golden brown, about 3 minutes. Whisking continuously, slowly adding the milk, until the sauce thick and bubbling. Add the Broccoli and kale and continue to cook, stirring often, for about 5 minutes. Take off heat and using an hand blender, puree the vegetables. until smooth. Add 2 1/2 cups of cheddar cheese, and mustard. Whisk until cheese melted and smooth. Season with salt and pepper to taste.
4. Pour the cheese sauce over the pasta and blend well. Pour into the baking dish. Sprinkle with the remaining cheddar cheese and Parmigiano-Reggiano over the top. Bake uncovered for abut 25 minutes, until bubbly. Let it sit for 10 minutes before serving.