Adding a dash of vanilla extract or a sprinkle of salt also won't disrupt your frosting's consistency so use what you like.

Sweetened condensed milk is a versatile ingredient that can be used in both the cake batter and frosting ... There’s also a ...

Just be sure you're using sweetened condensed milk and not evaporated milk, and let your tastebuds be your guide. Read the original article on Chowhound.

Add the evaporated milk, the milk, and the vanilla. Add the dry ingredients and mix well. Stir in lemon zest, lemon juice (leave 1 tablespoon for icing ... the same as sweetened condensed milk ...