While the chicken is cooking, cook the ziti in salted water according to package directions. Also begin the Alfredo sauce. Add 2 tbsp EVOO to a large saucepan and add the garlic. Cook until fragrant, about 1 minute. Add the flour and stir constantly for 1 minute to cook the flour. Mixture will be dry and lumpy. Whisk in the chicken broth one cup at a time and then the milk, whisking constantly so that there are no lumps.