Pat your chicken breast cubes completely dry with a paper towel and toss them in a small bowl with the garlic powder, onion powder, fine table salt, and black pepper until evenly coated.
Heat a large skillet over medium-high heat and add the avocado oil (or your preferred cooking oil) and one tablespoon of unsalted butter.
Once the butter is sizzling, add the seasoned chicken cubes in a single layer and sear undisturbed for two to three minutes until a golden crust forms on the bottom.
Toss the chicken bites and cook for one more minute before transferring them onto a clean plate, noting that the chicken does not need to be fully cooked through yet.
Turn the skillet heat down to medium and melt the remaining tablespoon of butter in the empty pan, swirling it through the leftover chicken juices.
Stir in the minced garlic continuously for thirty seconds until highly fragrant.
Add the uncooked white rice directly to the pan, stirring it constantly for one full minute to lightly toast the grains in the garlic butter.
Pour the chicken broth and milk straight into the skillet with the toasted rice.
Bring the liquid to a rapid boil, then immediately turn the heat down to low.
Return the seared chicken and any resting juices back into the pan, stirring gently to combine.
Pop a tight-fitting lid on the skillet and let it simmer undisturbed on low heat for twelve to thirteen minutes until the rice is completely tender and the broth is absorbed.
Remove the skillet from the heat, lift the lid, scatter your fresh baby spinach on top, and gently fluff the rice with a fork for thirty seconds until the spinach wilts into the creamy rice before serving warm.