Help with this icing recipe

[RobJ]

Hoping for some help. Our mom made these “toffee bars” every year for the holidays and they were and still are the family favorite, hands down. Ever since Mom passed we have tried to make them. The bars come out perfect but the icing never does. When Mom made it, it would set up with a perfectly even surface. Not glossy but a smooth flat sheen. It wasn’t hard like a chocolate bar but it was firm and cut with the bars. This recipe is what my sister copied from our mom’s of which the original has long been lost.
The issue is that four of us have tried making it and the icing never turns out. It’s sometimes crystalline and grainy, separating from the bars when you cut them. I’ve had it not set-up at all and stay a consistency of thick molasses oozing into the areas where you remove a bar from.
Can you tell from this recipe what we’re missing,doing wrong or what the proper technique for heating and stirring it is. Nobody has been able to get it right following these instructions. It would be very much appreciated by everyone in the family if we got some assistance on it. Thank you.

 

[retired baker]

if its grainy it needs 1/4 cup corn syrup to prevent crystallization.
too hard means it was boiled too long.
i use an infra red gun for accuracy, cook to 245f.

 

[EdwardGuerra]

ensure that you're accurately following the temperature instructions for the icing. use a candy thermometer to monitor the temperature closely it sounds like achieving the right consistency is crucial for this recipe.

 

[Mona]

It sounds like your icing might be having issues with crystallization or temperature. Try using a heavy-bottomed pan to ensure even heating, and avoid stirring once the sugar mixture starts boiling to prevent graininess. Use a candy thermometer to get the mixture to the right temperature, and consider adding a bit of corn syrup or cream of tartar to help with smoothness. Let the icing cool slightly before spreading it, and make sure your ingredients are fresh. Testing a small batch first can help you tweak the recipe. I hope these tips help you get that perfect finish your mom’s icing had!