Heat the butter in a frying pan.
Saute the onion until softened. Add the garlic and continue sauteeing for another half a minute.
Add the spinach to the pan. Sprinkle with salt and pepper. Cook over medium heat, stirring occasionally, until the spinach is wilted and quite dry. Spinach contains a lot of water and you need to let all the water evaporate before proceeding to the next step.
Turn down the heat to low. Drop the cream cheese into the spinach by pinches. Cook, stirring, until the cream cheese has melted and no lumps remain.
Use a small ice cream scoop to drop mounds of the cheesy spinach mixture on top of the hash browns. Sprinkle with chili powder before serving.