Add all the ingredients to a medium saucepan and heat over medium-low heat, stirring frequently.
Bring the mixture to a simmer, and simmer for 5 minutes, stirring occasionally.
Remove from heat and allow to cool for 15 minutes at room temperature. Strain the remaining toffee from the syrup using a fine mesh strainer or cheesecloth (there will be some left that didn't melt).
Use immediately, or transfer the syrup to a mason jar and place in the fridge for at least 4 hours, or until completely cooled. Once cooled, there will be milk solids floating on top of the syrup. Strain the syrup again or skim the top to remove the milk solids if desired (this is recommended for iced coffee). Store in the fridge for up to 2 weeks!