Step 1In a large pot of salted, boiling water, cook the pasta to al dente according to the package instructions, about 10 minutes. Drain and set aside.
Step 2Heat a medium, heavy-bottom pot over medium-high heat until hot. Saute the shallots in the olive oil until lightly colored, then add the heavy cream. Reduce the heat to a gentle simmer and reduce by half, 8 to 10 minutes.
Step 3Whisk in the crumbled cheese until melted and incorporated, then stir in the pasta.
Step 4Remove from heat and reserve the base, still in the pan, in a warm place.
Step 1Drizzle the chicken breasts with the olive oil, and season each side of each breast with a pinch each of salt and pepper. Sprinkle over the chopped parsley and rosemary. Grill the chicken over moderate heat until the flesh is firm and the juices run clear, and a thermometer inserted reads 165 degrees. Remove from heat, cover and keep warm until needed.
Step 1In a medium saute pan, cook the pancetta in the oil over medium-high heat until crisp, 5 to 7 minutes
Step 2Strain the pancetta, leaving any fat in the pan.
Step 3Heat the pan with the fat over medium-high heat and sprinkle over the bread crumbs.
Step 4Saute the bread crumbs until darkened and toasted, about 1 minute. Remove from heat and drain the bread crumbs on a paper towel.
Step 5Heat the macaroni base over medium heat until hot, stirring frequently. While the base is heating, slice the chicken into strips.
Step 6Stir the chicken into the base, then stir in the crisp pancetta, parsley and white truffle oil, tossing to coat.
Step 7Divide the mac 'n' cheese among 4 serving bowls and top with the crisp bread crumbs. Serve immediately.