Place squash cubes on a large aluminum foil-lined jelly-roll pan coated with cooking spray. Drizzle squash with 1 teaspoon oil, and sprinkle with 1/4 teaspoon salt and 1/4 teaspoon black pepper. Toss to coat.
Bake at 425° for 25 to 30 minutes or until squash is tender and golden, stirring occasionally.
Heat remaining 2 teaspoons oil in a large nonstick skillet over medium-high heat; add leek, and sauté 5 minutes or until tender and lightly browned. Add garlic, and sauté 1 minute. Remove from heat, and set aside.
Process butternut squash, vegetable broth, and half-and-half in a food processor until smooth.
Cook pasta according to package directions, omitting salt and oil. Add peas to boiling water during last 2 minutes of cooking time; drain. Return pasta and peas to pan. Stir in leek mixture, remaining 1/2 teaspoon salt, remaining 1/4 teaspoon black pepper, 1 tablespoon chopped sage, and crushed red pepper. Add processed squash mixture, tossing to coat. Sprinkle with Italian three-cheese blend. Garnish, if desired, and serve immediately.