Hopefully this can help someone.
I was making a double batch of SMBC. I heated my eggs and sugar. I set my bowl in a sink with cold water to cool a bit - I find I don't have to whip as long this way. I whipped my egg and sugar mixture and marveled at how beautiful it looked. So glossy and perfect, nicer than usual. I added my butter and ended up with a bowl of soup with little peas of butter. No matter how long I beat it just would not mix and thicken. It was a mess. As I was thinking about what could have happened I realized I used 1.5 cups of sugar instead of 2.5.
I figured that I would have to dump the batch and start over. I really didn't want to wait for a pound of butter to thaw so I tried to think of a way to salvage the mess. The only thing it needed was more sugar. You can't add a cup of sugar at this point and expect it to not end up with the texture of sand in butter can you? Then it hit me. If the sugar was finer maybe it would dissolve. I could add powdered sugar but I had no idea how much to add and its such a mess. What I came up with was putting my 1 cup of sugar into the Magic Bullet and blending it till it was fine, but not as fine as powdered sugar.
I crossed my fingers and poured it in the bowl. I put the whip back on and mixed it till it started to thicken. I switched to the paddle and let it go. It took a little while but it turned out great.
Have a great day all!