Coat lamb loins with olive oil, lemon juice, and fresh rosemary leaves.

Cover the lamb and chill in the refrigerator for at least 1 hour, or preferably overnight.

Melt 2 1/2 tbsp of butter in a large pan over medium-high heat.

Add the finely chopped onion and minced garlic to the pan.

Sauté the onion and garlic for 3-4 minutes, or until they become tender and translucent.

Add the Arborio rice to the pan and cook, stirring continuously, for 1 minute.

Pour in the dry white wine and cook for 1-2 minutes, until almost completely evaporated.

Gradually add the hot chicken stock (combined with water), 1 cup at a time, stirring continuously after each addition.

Allow the liquid to be absorbed before adding the next cup of stock.

Continue stirring and adding stock until all the liquid has been absorbed, approximately 20 minutes.

Preheat your grill to medium-high heat.

Remove the lamb loins from the refrigerator.

Place the lamb loins on the preheated grill.

Cook for 2-3 minutes per side for medium doneness, or until the lamb is cooked to your desired level of doneness.

Remove the lamb from the grill and let it rest for 5 minutes before slicing.

Stir the remaining butter, grated Parmesan cheese, and roughly chopped fresh parsley into the risotto.

Serve the sliced grilled lamb loin immediately on top of the creamy Risotto Milanese.