Preheat oven to 400°F Spray 8-inch square baking dish with nonstick spray. Bring large saucepan of salted water to boil.
Meanwhile, heat oil in medium skillet over medium heat. Add panko and cook, stirring occasionally, until toasted, about 4 minutes; set aside.
Add squash to boiling water; cover and return to boil. Cook, uncovered, until squash is very tender, about 10 minutes.
Meanwhile, combine broth, Cheddar, Pecorino, cream cheese, mustard, salt, and cayenne pepper in blender. With slotted spoon, transfer cooked squash to blender and puree. (Leave water in pan.).
Bring water back to boil. Cook pasta half the directed time on package; add cauliflower during last minute of cooking time. Drain; return to pot. Stir in puree and toss to coat. Spread pasta mixture in prepared baking dish; top with crumb mixture and spray with nonstick spray. Bake until top is golden and casserole is bubbling, about 25 minutes.