Put the olive oil and onion in a 4-quart saucepan and place over medium heat. Sauté until the onion turns to a rich golden color, about 5 minutes. Add the garlic, stir well for a few seconds, then add the tomatoes and rosemary, and season with salt and pepper. Cook until the tomatoes have reduced and begin to separate from the oil, 20 to 25 minutes.
Fill a pot for the pasta with about 6 quarts of water, cover, and place over high heat.
Add the chick peas to the sauce and cook for another 5 minutes. Scoop up about half of the beans and pass them through a food mill back into the pot. Alternatively, you can purée them in a food processor. Cook for another minute then remove from the heat.
Add 2 tablespoons salt to the boiling pasta water, add the tagliatelle, and stir until all the strands are submerged. Cook until al dente. When the pasta is done, drain well, toss with the sauce and the Parmigiano-Reggiano, and serve at once.