Yum. I make something similar called cheese eggs a la king, only difference is adding cheese and using cream of mushroom soup instead of the butter and flour mixture. My boyfriend wants me to try adding chopped, cooked bacon to it next time I make it.
This is almost identical to the creamed eggs on toast my family likes. Make up a white sauce (melt butter, add flour, add milk), then add in the hard boiled eggs, sliced whole, and serve over toast with salt and pepper to taste.