Prepare the macaroni by following the instructions on the package, then drain and keep aside.
In a medium-sized saucepan, melt the butter over low heat and gradually add flour, stirring constantly until the mixture thickens.
Increase the heat to medium and add milk, half a cup at a time, stirring constantly until the sauce starts to simmer and thicken.
Add the mustard and seasonings to the sauce.
Remove the saucepan from the heat and mix in the cheddar and parmesan cheese until fully melted.
Add the cooked tortellini to the cheese sauce and mix until fully coated. Your delicious mac and cheese is ready to serve.