In a large saucepan melt butter. Whisk in brown sugar and salt. Scrape vanilla seeds and add to mixture. Stir over medium heat for 5 minutes until mixture is the texture of sand.
Reduce heat to low. slowly pour in heavy cream whisking constantly. Mixture may seize just keep whisking. Whisk in whole milk.. Remove from heat. Whisk in egg yolks all at once whisking fast so they don't cook.
Pour into prepared ramkins. Pour hot water around ramkins in pan 1/2 way up the ramkins. Cover with foil and bake for 50 minutes.