In which Meredith fails at cheese sauce

So, after a rousing evening of bookcase-painting, I decided to reward myself with some tasty pasta in cheese sauce with kielbasa. In the past, I have had great success concocting this dish with alfredo sauce (melt butter, add heavy cream, grate in Parmesan until thickened), and I recently discovered that the same process works very well with whole milk and smoked Gouda -- it produces a thin, slightly sweet sauce which complements the sausage nicely. Tonight, after considering the (spartan, mostly consisting of beer and Red Bull) contents of my fridge, I settled on a hunk of sharp Cheddar. Melt, pour, grate grate grate, stir stir stir ....

... and I was suddenly disturbed to notice the contents of the pan separating into a curdled, gloppy mess. It had the look of what happens when one pours peppermint Schnapps into Bailey's, only with a yellowish, Cheddary cast to it. I kept it on low heat, attempting to prevent it from coming to a boil, stirring away, wondering whether this were perhaps some pupal stage between ingredients and proper cheese sauce, but eventually came to the conclusion that the cheese sauce had died aborning.

Where did I go wrong? Cheese sauce, how did you elude me? Is whole milk simply not fit to support a proper Cheddar emulsion? Might the fact that the milk was a couple of days past its sell-by date have had anything to do with it, despite the fact that it smelled fine? How can I correct my wrongdoing and stand once more among the ranks of the successful saucerors?

Even now, the failed cheese sauce sits atop my stove, mocking me with its sickly yellow whey. I eat my penne dry, and shudder in fear.

whitebreadchef? sandwichboy? slithytove? enochsmiles? czarina69? Anyone? Can anybody hear me?

Hello?

I --