Preheat oven to 375 degrees F. Spray a 1 1/2 or 2 quart baking dish with nonstick cooking spray.
Cook pasta as directed on the package instructions. Cook to al dente. Drain well.
In the prepared baking dish, alternate cooked and drained pasta with half of the shredded cheese.
Melt butter in a saucepan or skillet over low heat.
Add flour, and stir until lightly browned.
To the flour, slowly add milk, whisking constantly.
Let the mixture come to a low boil for one minute while stirring. Mix in salt and pepper.
Add remaining cheese, and stir until melted into the sauce.
Pour sauce over the cooked pasta and cheese mixture.
Bake, uncovered, for 15 - 25 minutes or until golden brown and bubbly.
Let the casserole sit for 5 - 10 minutes at room temperature before serving.