Simmer chickpeas in water to cover by 2 inches in a medium pot, partially covered with lid, adding more water if necessary, until tender, 1 to 1 1/4 hours. Drain chickpeas. 

Combine broth and 2 1/2 cups water in a medium pot; bring to a simmer.  

 

In a large saucepan, heat oil and butter over medium-high heat until butter is melted. Reduce heat to medium-low, add onion and cook, stirring occasionally, for 5 minutes. Add rice and cook, stirring constantly, until rice is translucent, about 5 minutes more.  

 

Add wine and cook, stirring, until mostly absorbed, about 1 minute. Add 1 cup broth mixture and cook, stirring constantly, until liquid is mostly absorbed, about 4 minutes. Add 1/2 cup broth mixture and cook, stirring, until mostly absorbed.  

 

Add another 1/2  cup broth mixture, chickpeas, walnuts and tomato paste; cook, stirring, until liquid is mostly absorbed.

 

Continue adding broth mixture by 1/2-cupfuls, stirring constantly, until rice is tender yet still slightly firm to the bite (there will be broth mixture leftover). Remove from heat. Stir in cheese and sage. Season with salt to taste. (Thin risotto with some of the remaining broth, if desired.) Serve immediately with pepper and extra cheese.