Line a 9x13-inch baking dish with parchment paper, leaving some overhang for easy removal later.
Arrange a single layer of 54 Club crackers on the bottom of the prepared baking dish, covering the entire surface.
In a medium saucepan over medium heat, combine the sweetened condensed milk, packed brown sugar, light corn syrup, and cubed butter. Stir continuously until the mixture comes to a boil, then let it boil for an additional 4-5 minutes, stirring constantly, until thick and glossy.
Carefully pour the hot caramel over the cracker layer, spreading evenly with a spatula if needed. Add another layer of crackers on top of the caramel, pressing down lightly.
In a microwave-safe bowl, heat the semi-sweet chocolate chips in 30-second intervals, stirring in between, until melted and smooth. Be careful not to overheat.
Pour the melted chocolate over the second layer of crackers and spread evenly with a spatula.
Refrigerate the dish for at least 2 hours to allow the caramel and chocolate to set. Once firm, lift the candy out using the parchment paper overhang and cut into squares or bars.