Preheat oven to 375°.

Combine squash, broth, milk, and garlic in a medium saucepan; bring to a boil over medium-high heat. Reduce heat to medium, and simmer until squash is tender when pierced with a fork, about 25 minutes. Remove from heat and let cool for about 10 minutes.

Place the warm squash mixture in a blender. Add salt, pepper, and Greek yogurt. Blend until smooth. Place blended squash mixture in a bowl; stir in cheeses and mix until combined.

Cook pasta according to package directions, drain well. Add pasta to squash mixture, and stir until combined. Spread mixture evenly into a 13 x 9-inch glass or ceramic baking dish coated with non-fat cooking spray.

Sprinkle panko evenly over the hot pasta mixture. Lightly coat topping with cooking spray.

Bake at 375° for about 20 minutes or until bubbly. Serve immediately.