In a skillet, cook bacon over medium heat until crisp. Remove with a slotted spoon to paper towels; drain, reserving 1 tablespoon drippings. In drippings, saute onion until browned; drain.
Cut eight asparagus spears into 4-inch long spears for garnish. Cut remaining asparagus into 1-inch pieces.
In a saucepan, cook all of the asparagus in a small amount of boiling water until crisp tender; drain.
In a bowl, toss the bacon, onion, asparagus pieces, cheese, flour, salt and pepper. Pour into pastry shell.
In a bowl, beat eggs and half and half; pour over bacon mixture. Top with asparagus spears in a pinwheel design.
Bake at 400 degrees for 30-35 minutes or until a knife inserted near center comes out clean and crust is golden brown. Let stand 10 minutes before serving.