In a small saucepan, stir evaporated milk together with corn syrup, brown sugar, granulated sugar and pinch of salt. Set over medium high heat and bring to boil. Reduce to simmer and cook 3 minutes. Remove from heat and stir in chocolate, butter, vanilla and peppermint. Whisk until smooth. To ensure sauce is smooth, strain or blend. Pour into jars and store in refrigerator until ready to serve.