Cook macaroni according to package directions; drain. Mix panko, parsley, and olive oil together in a bowl. Meanwhile, in another saucepan, melt butter over medium heat. Stir in flour until smooth; gradually whisk in milk. Bring to a boil, stirring constantly. Cook and stir for 2 minutes or until thickened. Add cheese; cook and stir until melted. Stir in macaroni and sausage. Spread panko mixture on top and bake at 350 degrees F for 25 minutes. Enjoy.