While it's heating, slice the cauliflower from top to bottom in 1-inch thick slices. Brush both sides with oil; salt and pepper to taste.
Place the cauliflower slices in the hot skillet, pressing them down. Cook for 3-4 minutes, until nicely browned; flip them over and cook till brown and tender. Remove from skillet and keep warm.
While the cauliflower is browning, slice broccoli in the same way as the cauliflower and brush with some remaining oil.
Cook the broccoli just as you did the cauliflower - till brown on both sides and tender. Remove from skillet & place on platter with the cauliflower.
Add remaining oil (about 2 tsps) to the skillet and sauté the garlic, stirring constantly, till lightly browned - 1-2 minutes. Transfer to a paper towel to absorb any remaining oil and sprinkle with salt and pepper.
Arrange the broccoli around the outside of a serving platter and place the cauliflower in the center of the circle.
Sprinkle with garlic pieces & drizzle with the olive oil.