
Heat oven to 400°F. Halve the squash lengthwise and scoop out the seeds. Microwave the halves cut-side down in a dish with 1/4 inch of water, covered, 12-15 minutes until tender.
Meanwhile, brown the sausage and diced onion in a skillet 8 minutes until the sausage reaches 160°F, then add the marinara and spinach and simmer 5 minutes.
Scrape the squash into strands with a fork, leaving them in the shells.
Spoon the sausage sauce over the squash, top with mozzarella and Parmesan and broil 3-4 minutes until bubbly.
Serve right in the shells, scooping portions onto plates.
Photo: DinnerDrop