Preheat your oven to 375°F (190°C).
Slice the zucchinis in half lengthwise and scoop out the flesh using a spoon or ice cream scoop, creating 'boats.' Be careful not to puncture the skin. Reserve the scooped-out zucchini flesh.
In a mixing bowl, combine the shredded chicken, diced tomatoes, chopped onions, minced garlic, dried oregano, smoked paprika, salt, and pepper. Mix well. Then, add half of the mozzarella cheese and the reserved zucchini flesh to the mixture. Stir until well combined.
Place the hollowed zucchini halves on a baking sheet. Drizzle them lightly with olive oil and sprinkle a little salt and pepper inside each boat.
Fill each zucchini boat with the chicken mixture, packing it well. Top each filled boat with the remaining mozzarella cheese and a sprinkle of grated Parmesan cheese.
Cover the baking sheet loosely with aluminum foil to prevent burning. Bake in the preheated oven for 20 minutes.
After 20 minutes, remove the foil and bake for an additional 5 minutes or until the cheese is bubbly and golden.
Once done, take the baking sheet out of the oven and let the boats cool slightly before serving.