How to Make It
Preheat oven to 400°.
Remove beans from pods; discard pods. Cook beans in boiling water 1 minute. Remove beans with a slotted spoon. Plunge beans into ice water; drain. Remove tough outer skins from beans; discard skins. Set beans aside.
Arrange prosciutto in a single layer on a baking sheet coated with cooking spray; bake at 400° for 7 minutes or until crisp. Set aside.
Bring broth and water to a simmer in a medium saucepan (do not boil); keep warm over low heat.
Melt butter in a medium sauté pan over medium-high heat. Add leek and garlic; sauté 3 minutes or until tender. Add rice and thyme; cook 2 minutes, stirring constantly. Reduce heat to medium. Add white wine; cook 1 minute or until liquid is nearly absorbed, stirring constantly. Add broth mixture, 1/2 cup at a time, stirring frequently until each portion of broth is absorbed before adding the next (about 20 minutes total). Stir in beans, salt, and pepper; cook 2 minutes, stirring frequently.
Remove from heat; stir in arugula and cheese. Top with prosciutto.