Boil pasta, drain, and set aside when done. Work on sauce directions below while it boils.
Melt butter in a medium-large sauce pan. Add in flour and whisk until consistent. Add in milk and continue to whisk bringing the mix to a boil. Once boiling turn heat down to medium and allow to thicken a couple minutes.
Add the cheese to the white mixture and stir with a spoon or spatula until thoroughly combined.
Let the cheese simmer over low while you work on the crab.
Add shredded crab and olive oil to a small saute pan and cook a couple minutes over medium heat just to allow olive oil to coat and warm lobster - you don't want to over cook it.
Add in the noodles & crab to the cheese mixture and stir until combined.
Pour the macaroni into a baking dish like pictured above, or just a 9X9 baking pan.
If you want to sprinkle a little cheese on top or add bread crumbs do so now. (IF you add breadcrumbs spray cooking spray over the top of breadcrumbs, they brown better when moist).
Lightly salt and pepper the top and bake 20-25 minutes until breadcrumbs start to brown.