To make the rice: Heat the oil over medium-high heat in a large saucepan with a heavy bottom or small Dutch oven. Add the rice and the salt and stir to coat. When the rice starts to appear opaque and chalky, add enough cold water to cover the rice by the width of 2 fingers (about 1-inch). Bring to a rapid boil, and boil-without stirring!-until the water level reaches the level of the rice. Stir the rice once and reduce the heat to low. Cover and cook 20 minutes.
Meanwhile, make the spinach mix: Heat the olive oil in a large skillet over medium-low heat. Add the garlic, stirring so it doesn't stick, and cook until fragrant. Stir in the spinach and season with salt and pepper, to taste. Raise the heat to medium-high and cook until the spinach is just heated through. Don't overcook or the spinach will discolor.
Once the rice has finished cooking, fold the spinach into the pot. Fluff the rice so that the spinach is evenly distributed. Taste and season with additional salt and pepper if necessary. If you like, add a couple of drizzles of olive oil to give the rice a little gloss.