In a heated pan pour a tablespoon of olive oil and 20 g of butter, add finely chopped onion and garlic, and fry for about 10 minutes on low heat. Add the rice, turn up the heat and cook briefly to become shiny, stirring constantly.
Pour in the wine and simmer, stirring constantly, until alcohol evaporates.
In a hot vegetable broth add the saffron, then pour a ladle of broth to the rice, and stir until the rice absorbs all the liquid. Continue adding broth ladle by ladle, stirring constantly. If you run out of broth ( although this amount should be more than enough), add some hot water. This takes about 15 minutes.
Add the shrimps and stir well to toss.
When the rice is done, remove the pan from the heat, add the rest of the butter and the rocket, stir, season with some salt if necessary. Cover and let sit for a few minutes before serving.