Preheat your oven to 200°C (convection mode).
Wash the very large zucchini, cut it in half lengthwise using a sharp knife on a cutting board, and scoop out the inner flesh with a spoon to create boats. Reserve the flesh, roughly chop it, and set aside.
Peel the onion and garlic. Finely dice the onion and mince the garlic with a knife.
Wash the bell pepper, remove the seeds, and dice it into small pieces.
Heat 1.5 tbsp olive oil in a pan over medium heat. Add the diced onion and minced garlic, sautéing for 2-3 minutes until translucent.
Add the diced bell pepper and chopped zucchini flesh to the pan. Cook for another 5 minutes, stirring occasionally with a wooden spoon.
Stir in the 200 g vegan minced meat, breaking it apart with the spoon, and cook for 5 minutes until slightly browned.
Add 100 g canned diced tomatoes, 3/4 tsp thyme, 3/4 tsp oregano, 1/3 tsp smoked paprika, and season with salt and pepper to taste. Mix well and let simmer for 3 minutes.
Place the zucchini boats on a baking sheet. Fill each boat generously with the vegan minced meat mixture using a spoon.
If using, sprinkle 35 g grated vegan cheese evenly over the filled zucchini.
Bake in the preheated oven for 30 minutes, or until the zucchini is tender and the top is golden.
Remove from the oven using oven mitts and let cool for 5 minutes before serving.