One of the keys to get the flour-y taste out is cook the flour out a bit before you add the dairy. It doesn't take long at all. In your sauce pan, melt some butter, but don't brown it. Add the flour and stir for about a minute, don't let the rue brown either. Now, slowly add your dairy. You need a little garlic in there, a pinch of powder would be cool. Now, Italian blend cheese is OK, but I like to use fresh Parmesan and Romano cheese. Overall, if you do what you already did except cook out the flour a bit I think you'll like the outcome.