In a large bowl, combine the oil, salt, garlic powder, cayenne and chili powder. Whisk well to combine.
Place the brussels sprouts into the olive oil mixture and coat the brussels well.
On a rimmed baking sheet, spread the brussels sprouts in a single layer. Cover the baking sheet tightly with foil.
Cook the brussels sprouts for 20 minutes. After 20 minutes, remove the foil and lower the heat to 425 degrees. Continue to roast, uncovered, for 15 to 20 minutes (until browned to your liking), stirring every 5-8 minutes.
Top the brussels with a squeeze of lemon juice and serve warm with a side of Greek yogurt topped with lemon zest.