Pat the chicken pieces dry and toss with the paprika, garlic powder, onion powder, 1/2 teaspoon of the salt, and the black pepper until evenly coated.

Heat the olive oil in a Dutch oven or deep skillet over medium-high heat. Add the chicken in a single layer and cook, turning once, until golden on the outside, about 5–6 minutes. It doesn't need to be cooked through yet — the simmer finishes it. Transfer to a plate.

Reduce the heat to medium. Add the onion and bell pepper to the pot; cook until softened, about 3 minutes, scraping up the browned bits. Stir in the minced garlic and cook 1 minute more, until fragrant.

Stir in the rinsed rice and toast for 1 minute, stirring, until the grains look slightly translucent at the edges. Pour in the chicken broth and the remaining 1/2 teaspoon salt, scraping the bottom of the pot. Return the chicken and any accumulated juices to the pot and bring to a lively simmer.

Reduce the heat to low, cover, and cook until the rice is tender and the liquid is absorbed, about 13 minutes. Don't lift the lid for the first 10 minutes — trapped steam is what cooks the rice evenly.

Remove the pot from the heat. Pour in the milk and sprinkle the cheddar over the top; stir gently until the cheese melts into a creamy sauce, about 2 minutes. Rest 2 minutes, then fluff with a fork, shower with green onions, and serve straight from the pot.