Line a 8 x 8 square pan with tin foil (enough so it hangs out over the edge), and spray it with cooking spray.
Combine the butterscotch chips, cookie butter, and sweetened condensed milk in a small saucepan over medium low heat.
Stir until it is melted and combined.
Add vanilla and stir until combine.
Pour into the prepared pan and let set for four hours.
Remove the fudge from the pan. Cut into four pieces. Cut each fourth into 9 pieces (3 by 3). Enjoy right away or store in an airtight container for up to 2 weeks at room temperature.