1. Preheat your oven to 375°F (190°C).
2. Slice the zucchinis in half lengthwise and scoop out the flesh, leaving a small border to create the “boats.” Set aside the scooped flesh.
3. Place the zucchini halves on a baking sheet, brush with olive oil, and sprinkle with a pinch of salt. Bake for 10 minutes to soften them slightly.
4. While the zucchini bakes, heat a skillet over medium heat. Add the ground beef and cook until browned, breaking it up with a spoon.
5. Add the chopped onion and garlic to the beef, cooking until the onion is translucent.
6. Stir in the marinara sauce, cumin, chili powder, salt, and black pepper. Let the mixture simmer for about 5 minutes.
7. Remove the zucchini from the oven and fill each boat with the beef mixture. Top with shredded cheddar cheese.
8. Return to the oven and bake for an additional 10-15 minutes, or until the cheese is melted and bubbly.
9. Garnish with fresh cilantro before serving.

One tip from my own experience: if you find your zucchinis are too watery, try salting them and letting them sit for a few minutes before baking. This helps draw out excess moisture, ensuring your boats are firm and delicious.