Place squash in a Dutch oven; cover with water. Bring to a boil. Cover, reduce heat, and simmer 35 minutes or until tender. Drain.
. Preheat oven to 400°.
. Cook rice according to package directions, omitting salt and fat.
. While squash and rice cook, melt butter in a medium, heavy saucepan over medium heat. Add shallots and garlic; sauté 2 minutes or until tender. Add flour; cook 1 minute, stirring constantly with a whisk. Gradually add milk; cook 5 minutes or until mixture is thick, stirring constantly. Remove from heat; stir in parsley and next 4 ingredients.
. Scoop out squash pulp; discard squash peel. Combine squash, cheese, and garlic-butter sauce in a large bowl; beat with a mixer at medium speed until well blended. Stir in rice. Pour squash mixture into a 1 1/2-quart casserole coated with cooking spray.
. Bake at 400° for 45 minutes or until edges are golden and top is set. Let stand 5 minutes before serving.