In your food processor fitted with the blade attachment, work in batches pulsing cauliflower florets until small pieces form.
Spray a rimmed metal baking sheet with oil before adding the riced cauliflower.
Season with a few (about 5 to 6) shakes of garlic powder and season with a few pinches kosher salt. Stir to combine.
Use a rubber spatula to spread the cauliflower rice in an even layer. Spray the cauliflower rice one last time before sliding the pan onto the bottom rack of your preheated oven and roast for 10 minutes.
Remove, stir and rotate the pan. Roast for another 10 minutes.