Bring large pot of water to boil over medium-high heat. Add pasta and cook per package directions. Drain and set aside.
Meanwhile, lightly grease medium skillet with butter, add mushrooms and cook over medium heat until brown. Set aside.
In stock pot over medium-high heat, steam kale with 1/3 cup water with lid on until it turns bright green.
In small saucepan, whisk together flour and milk. Cook over medium heat until warm, stirring constantly. Add garlic powder, cayenne pepper, black pepper and cheddar. Stir until cheese melts and is thoroughly combined. Pour cheese sauce over cooked pasta.
Add cooked mushrooms and kale, toss to combine. Crumble blue cheese over top, using your hands.
Divide among individual bowls and serve.