Try and chop all the veggies the same size, about 1/2" cube. Place sweet potatoes, squash, potato, red pepper, onions, corn, and whole garlic cloves on a large rimmed baking sheet and toss with 1-2 Tbsp olive oil and sprinkle with salt and pepper. Roast at 375°F for 20 minutes, then broil for the last 5-10 minutes or until they turn golden in color.