Cook pasta one minute less than the package directions. Drain, set aside.
In a large skillet, add the butter over medium high heat and melt. Add the onion, celery and ham. Saute until the vegetables soften, about 5 minutes.
Add the flour and cook one minute; stirring to incorporate the flour.
Add the milk and reduce the heat to medium. Add the salt, vinegar and thyme. Cook, stirring constantly but gently until the sauce thickens enough to coat the back of a spoon; 6 to 7 minutes. The sauce should gently simmer.
Turn off the heat and add the cheese; stir to melt.
Add the pasta and turkey and stir to coat. Transfer to an oven safe 9x13 casserole dish or bake in your skillet if it's oven safe.
In a food processor, pulse the bread slices to coarse crumbs. Add the melted butter and thyme. Sprinkle over the pasta.
Bake 25-30 minutes until bubbling around the edge.
Note 1: To make soft bread crumbs, run two or three slices of your favorite bread in a food processor or chop it finely with a knife. I used sourdough, but most breads will work. I don't recommend regular white sandwich bread.