Bring about 2 litres of slightly salted water to a boil. Wash the broccoli and then separate the florets from the stem, keeping the pieces as intact as possible.
Boil the broccoli stem for 5 minutes and the florets for 3 minutes. Drain the broccoli, reserving the cooking water (you will cook the risotto in this) and rinse the broccoli under cold water to stop cooking.
Finely dice the broccoli stem and chop the florets into small pieces. Put these to the side.
Heat the oil in a wide pan over a low-medium heat and fry the onion and celery for around 10 minutes or until softened. In the meantime, keep the broccoli cooking water on a low simmer in a separate saucepan to use as stock (for extra flavour, I like adding a halved onion).
Tip in the rice and stir around for 1-2 minutes (do not brown the rice).
Increase the heat slightly, add the wine and continue stirring for a couple of minutes until the liquid has been absorbed.
Add two ladlefuls of the stock, stirring constantly until most of the liquid has been absorbed. Continue cooking in this manner, adding a ladleful of stock at a time, stirring frequently.
When the rice is almost cooked (after about 15 minutes) add the chopped broccoli. Continue to cook with the remaining stock until the rice is al dente and the risotto has a moist creamy texture.
Take the risotto off of the heat and stir through the gorgonzola and most of the grana padano or parmesan (keep aside about 20 grams) for a minute or two, allowing the gorgonzola to melt and the texture of the risotto to become even creamier.
Plate the risotto and finish with cracked black pepper and the remaining grated cheese. Buon appetito!