Place oven rack in the top position and pre-heat to 450 degrees.
Dice onion.
Cut the zucchini in half (lengthwise).
Scoop zucchini seeds out with a spoon to create a "zucchini boat." Discard seeds.
Heat olive oil in a medium-sized pot. Add onions, salt, and pepper and cook for 4 minutes.
Add garlic and cook for 1 additional minute.
Add rice and Southwest Spice Blend to pot, and pour in vegetable stock (use the amount listed in the instructions for the rice). Stir to blend. Follow the rice's instructions for cook time.
Once done, remove rice from heat and keep covered until ready.
While the rice cooks, season the zucchini with olive oil, salt, and pepper and evenly coat.
Place the zucchini face down on a baking sheet.
Roast the zucchini on the top rack for 15-20 minutes (zucchini should be tender and browned).
While zucchini is in the oven, dice tomatoes, green onions, and cilantro and set aside.
Fluff rice with fork and season with salt and pepper. If desired, stir in 2 tbsp butter.
Remove zucchini from oven and flip over.
Stuff zucchini with rice. There will be remaining rice, which will later be used as a base on the plate.
Sprinkle zucchini and rice with cheese.
Place the baking sheet back in the oven and cook for another 2-3 minutes, until cheese is melted and slightly browned.
Divide remaining rice on plates to serve as the base. Place zucchini on rice, and add tomatoes, green onions, cilantro, pico, guacamole, sour cream, and/or hot sauce to taste.
