Directions

1. 1 Preheat oven to 375°F. Carefully pierce squash all over with a small sharp knife. (If too difficult to pierce, microwave squash on HIGH 3 to 4 minutes or until tender enough to pierce.) Place squash on foil-lined shallow baking pan.
2. 2 Bake 1 hour 20 minutes or until tender when pierced with a knife, turning halfway through cooking. Let cool slightly, about 20 minutes. Meanwhile, beat Seasoning, milk and egg in large bowl until well blended. Stir in tomatoes. Set aside.
3. 3 Cut squash in half lengthwise; remove seeds. Using fingers or a fork, shred squash flesh into long thin strands into the bowl with the egg mixture; stir to blend. Place squash shells, cut side up, back on the baking pan. Set aside.
4. 4 Melt butter in large skillet on medium-high heat. Add onion; cook and stir until translucent, about 3 to 5 minutes. Add spinach; cook and stir until wilted, about 2 minutes. Stir into squash mixture. Fill shells evenly with squash mixture. Top with cheese.
5. 5 Bake 30 minutes or until bubbly and lightly browned.