Tonight was my second attempt at making alfredo sauce. Both attempts seemed to be going well...good consistency, etc. I put it on the pasta and it seemed fine. However once it started to cool a little, it became gritty b/c the cheese didn't seem to have melted enough. Tonight I kept it on the stove a bit longer, hoping to avoid the grit. That didn't work either. What am I doing wrong? The flavor would have been fine, but I just couldn't get past the texture.