Preheat the oven to 400°F or 200°C. Line a baking sheet with parchment paper.Rinse broccoli and cauliflower heads, remove the leaves and the stem and cut them into florets. Pat them dry and add them to the baking tray.
Season with extra virgin olive oil, garlicpowder, salt, and black pepper. Toss with your hands, then spread florets across the sheet pan without overlapping. Try not to overcrowd the pan.
Roast vegetables at 400°F or 200°C for about 25 minutes until the florets are tender-crisp and slightly charred.
Transfer onto a serving platter, sprinkle with a pinch of red pepper flakes and a squeeze of lemon juice, and/or toasted shaved almonds.