Line a slow cooker with aluminum foil to create a foil bowl.
In a large mixing bowl, stir together melted butter and brown sugar until smooth. Add in vanilla extract and eggs and stir again until smooth. Stir in salt and flour until well combined.
Pour batter into the bottom of a foil lined slow cooker. Sprinkle chocolate chips on top. Secure a paper towel under the lid of the slow cooker.
Cook on high 2 1/2 to 3 hours until set in the middle. Use the aluminum foil to remove the cookies from the slow cooker. Cool at least 1 hour before cutting and serving.