Preheat the oven to 375ºF.

Whisk together the melted butter, brown sugar, vanilla, vinegar, and eggs in a medium bowl.

Place 18 frozen tart shells on a large baking sheet. Drop about 10 raisins into each tart shell and then distribute the filling mixture evenly on top throughout all 18 tart shells.

Bake the butter tarts in the preheated oven for 20-23 minutes or until the edges of the tart shell are golden brown and the filling has puffed up.

Let cool slightly or to room temperature before serving. Enjoy!