Preheat oven to 400 degrees and grab a deep baking dish (I recommend a 9x12 or 9x13 size). Slice the bell peppers in half, remove the insides, and cover the outsides with 1 tbsp of olive oil and a few sprinkles of salt. Place the peppers in the baking dish and transfer to the oven for 30-40 minutes to soften.
Meanwhile, heat the remaining olive oil in a large skillet over medium heat. Add the ground turkey and brown all over to cook completely, breaking it apart into small pieces. Add the salt, black pepper, garlic powder, oregano, and red pepper flakes and fully coat.
Remove the turkey from the skillet and set aside. In the same pan add in the yellow onion and sauté for about 5 minutes to soften. Add the rice and stir to combine, then mix in the nutritional yeast and a few sprinkles of salt.
Pour in the broth, water, and crushed tomatoes, stir to combine and cover the skillet. Cook for 20-25 minutes, stirring halfway through, to fully cook the rice.
Stir in the baby spinach and wilt down, then add back the ground turkey.
Fill each of the 8 bell pepper halves with the turkey and rice mix. Be sure to stuff as full as possible to use up all of the mix, but you may have some leftover (feel free to enjoy separately!).
Transfer back to the oven for 5-10 minutes to reheat everything, top with additional nutritional yeast if desired, then serve immediately for best results.