Combine butter, brown sugar, 1/4 c. heavy whipping cream and vanilla in a saucepan.

Cook on medium low heat for about 15 minutes, stirring constantly.

Remove from heat when the sauce coats the back of a spoon. Allow to cool completely.

Whip 2 cups of heavy whipping cream until if forms stiff peaks. 

Add sweetened condensed milk and whip until thick.

Add almost all of the sauce leaving a small amount for topping.

Whip until combined.

Pour mixture into a loaf pan that has been lined with wax paper. 

Drizzle remaining sauce onto the ice cream mixture and swirl.

Freeze for at least six hours and enjoy!