In a 4- to 6-quart electric pressure cooker cook leeks and garlic in hot butter over medium heat until tender. Stir in rice; cook and stir 1 minute more. Stir in wine, broth, and pepper. For a stove-top cooker, cook directly in the pot. Lock lid in place. Set an electric cooker on high pressure to cook 6 minutes. For a stove-top cooker, bring up to pressure over medium-high; reduce heat enough to maintain steady (but not excessive) pressure. Cook 6 minutes. Remove from heat. For both models, release pressure quickly. Open lid carefully. Top with cheese and Arugula Gremolata.
Slow 1 1/4 hour low cook time
In a large skillet cook leeks and garlic in hot butter over medium heat 3 to 5 minutes or until tender. Stir in rice; cook and stir 1 minute more. Spoon into a 31/2- or 4-qt. slow cooker. Stir in broth, wine, and pepper. Cover and cook on high 1 1/4 hours or until rice is tender. Remove crockery liner from cooker, if possible, or turn off cooker. Let risotto stand, uncovered, 15 minutes before serving. Top with cheese and Arugula Gremolata.
In a bowl stir together the arugula, prosciutto, pine nuts, lemon zest, and garlic.