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!

I am glad this worked for you.When I first starting baking if I messed up one little thing I would throw it away. Then once I really messed up a cheesecake and it came out fine. instill mess things up once in a while though. I have learned to put all my ingredients a large cookie sheet and set them aside as I'm done. but before I dump anything in the bowl,if I am

 the least bit doubtful I measure again. It's easier with a scale.

AJust yesterday I had a buttercream "save" as well! I set a batch of frozen smbc out overnight to come to room temp. In the morning I went ahead and tried to whip it up again even though deep down I knew it was still a bit chilly. (room temp at 5 am in the winter! ). Sure enough, it broke into little butter gravel and soupy sugar water. Almost went in the trash, but I decided not to give up so easily. I thought it was irretrievably broken down, but not much to lose by playing with it. I put a little space heater on the counter a foot or so away from the bowl, and kept mixing. Lo and behold, withIn a few minutes it started to come together and I turned off the heater. Continued to mix another minute or so and it turned out perfectly! Maybe could have saved a few batches over the years, but now I know!