Step 1

Over medium-low heat, melt the butter and brown sugar and a medium saucepan.

Step 2

Add the sweetened condensed and corn syrup.

Step 3

While the sauce thickens over the next 5-7 minutes, continue to gently whisk the mixture until it thickens and the sugar melts.

Step 4

Take it off the heat, allow it to cool a bit. It will thicken as it cools too.