Preheat your oven to 425℉. If using a cast iron baking sheet you will also want to preheat it in the oven.
Peel the garlic and cut it into chunks or thick slices. Cut the stems off the green beans and cut them in halves. Cut the cauliflower into bite size florets.
In a large mixing bowl, add the cauliflower florets, green beans, and garlic.
Season generously with salt, pepper, and garlic powder.
Add around 1/2 cup of olive oil to the veggie mixture and toss together until everything is well coated. Add more olive oil as needed until the cauliflower, green beans, and garlic are all coated.
Spread the cauliflower and green bean mixture evenly onto your baking sheet.
Roast in the oven for 25 minutes or until the vegetables are tender and golden.
Notes
I prefer to roast these veggies on a cast iron baking sheet like this one on Amazon.