Preheat the oven to 220ºC with air if you have it. Line a large tray with baking paper. Cut the broccoli, separating the florets into portions not much larger than a bite, leaving part of the stems and keeping the trunk.
It is difficult to get identical florets, but even positive that we have portions of different sizes to obtain different doneness. The largest florets will have to be cut in half, going through their stem.
For the trunk, cut the outermost and hard part until it looks whiter and more tender, not stringy. Cut into sticks in one bite. Wash everything well with water, gently, and drain and dry with a clean cloth.
Spread in a single layer on the tray, drizzle with a generous stream of olive oil and season with salt and pepper. Add the whole peeled garlic cloves, cut in half or thickly sliced, depending on whether you prefer to give more or less flavor. To save time you can season with garlic powder. Stir well with your hands.
Bake 15 minutes; if the oven is not very homogeneous, rotate the tray halfway through the time. Scoop out and remove the smaller pieces. Flip the larger ones and bake again for about 5 minutes, lowering the power to 200ºC. Season with the juice of half a lemon and serve with grated zest from the other half; add grated Parmesan if desired and more pepper.