In a large skillet over medium heat, cook the sausage, stirring and breaking it apart until cooked through, about 5-10 minutes.
If there is excess grease, drain most of it, then add the diced onion and bell pepper. Cook, stirring occasionally, until the vegetables soften, about 5 minutes.
Add the rice, white beans, diced tomatoes, Italian herbs, garlic powder, salt, red pepper flakes, and water. Stir well to combine. Cover and let it simmer for approximately 40 minutes, stirring occasionally, until the rice is nearly tender and most of the water has evaporated.
Gradually add the spinach, a few handfuls at a time, allowing it to wilt. Cover and let the rice finish cooking off the heat.
Serve the dish warm.
Notes
For a milder version, you can use mild Italian sausage instead of spicy.