Preheat your oven to 375ºF. Slice the squash in half, remove the stem, scoop out and discard the seeds.
Using a large casserole dish, place the squash halves cut-side down into the dish, and pierce several shallow holes into the squash skin with a fork. Then, fill the dish 1/4" high with water.
Bake for 35-50 minutes, depending on the thickness/size of your squash. Test to see if it's done by gentle poking the squash with a fork, if it is tender, it will move a bit and be slightly soft. This means it is ready.
While the squash is baking, turn on your grill, clean it and spray with a thin layer of cooking oil.
Cut the stems out of the tomatoes and grill them until they are charred on most sides. It is okay if they explode, but it's better to have them whole for the sake of taking them off of the grill.
Once the tomatoes are done roasting, place them on a plate and give them 5 minutes to cool slightly.
Get a medium sauce pan ready over medium heat, with the teaspoon of olive oil heating. Once the plate is hot enough to sizzle a water drop, add the onions and garlic to it.
Saute until the onions are clear.
Carefully peel the skins off of the tomatoes and place them into a blender with the sun-dried tomatoes. Puree until completely smooth, or if you like your marinara chunky pulse until you get your desired texture.
Pour the mixture into the sauce pan with the onions and heat to a simmer. Cook the mixture for 5 minutes, stirring occasionally so that it reduces and thickens.
Stir the basil, oregano, sea salt, red pepper and black pepper into the sauce. Lower the heat so that the mixture is at a low simmer. Cook for 5 minutes.
When the squash is done baking, take it out of the oven and let it cool for 10 minutes; it will be very hot.
Next, take a fork and scrape the squash into a colander. Once done, press the squash lightly to squeeze out some extra moisture.
For serving, use 1 1/2 C., give or take, of the squash and plate it with a large scoop of marinara on top. Use fresh, chiffonade cut basil as an optional garnish.