Preheat oven to 350°F (175°C) and grease a 9x13 inch baking dish with non-stick spray or butter.

In a large mixing bowl, whisk together the light corn syrup, granulated sugar, eggs, melted butter, and vanilla extract until the mixture is homogeneous.

Fold the chopped pecans into the syrup mixture using a spatula.

Pour the pecan mixture into the bottom of the prepared baking dish and spread into an even layer.

Sprinkle the dry yellow cake mix evenly over the top of the liquid pecan layer, ensuring no large clumps remain.

Distribute the chilled butter slices across the entire surface of the dry cake mix to ensure uniform hydration and browning during the baking process.

Bake in the center rack for 45 minutes or until the topping is golden brown and the pecan filling is bubbling at the edges.

Remove from the oven and allow the cake to rest for at least 30 minutes to allow the custard base to set before serving.