Preheat oven to 385° F
Chop the potatoes and brussels sprouts into cubes. The smaller the brussels sprouts are the better they cook!
Keep all the vegetables in separate piles. Dump the potatoes in a bowl and drizzle enough olive oil to cover. Mix it thoroughly. Put the potatoes on one side of the cookie sheet.
Do the same thing with the brussel sprouts and green beans, keeping them all separate so you can add them to the cookie sheet in sections. (This makes it easier to remove them if they cook faster than the other.)
Once everything is on the cookie sheet, sprinkle salt and garlic powder on top.
Cook in the oven for 15-30 minutes. Sometimes the brussels sprouts will cook faster than the green beans and potatoes, so make sure to keep an eye on them.
When golden and crisped to perfection, enjoy! They go amazing with steak or chicken!