Cook elbow macaroni according to package directions for al dente. Drain the macaroni and mix in the diced tomatoes-cook over medium-high heat until the liquid from the tomatoes is mostly absorbed; set aside.
In a medium saucepan over medium heat, melt the butter and then whisk in the flour, cayenne pepper, and cook for about 1 minute or until golden. Slowly mix in the half and a half and the broth until smooth.
Bring the mixture to a boil, reduce the heat to a medium simmer and cook until mixture starts to thicken.
Remove from the heat and stir in the cheeses, 1 teaspoon of salt and one teaspoon of pepper; stirring until the cheese is melted.
Mix the cheese sauce with the macaroni and tomatoes and pour into a 13 x 9 casserole dish.
Bake for 15 to 20 minutes or until cheese is bubbly and starts to brown. (You might want to place the casserole dish on a sheet of aluminum foil in case it starts to bubble over, but I did not have a problem)