Preheat oven to 30 degrees. Spray a 9 x 13 baking dish with non-stick cooking spray.
In medium bowl, whisk together eggs, corn syrup, brown sugar, and vanilla until well combined.
Sprinkle 1/2 of the boxed cake mix into prepared baking dish evenly.
Pour 1/2 of the egg mixture over the cake mix in prepared baking dish. Top with 1/2 of the chopped pecans evenly.
Sprinkle remaining 1/2 box of cake mix over the chopped pecans.
Pour remainder of the egg mixture over the cake mix. Top with remaining chopped pecans.
Drizzle melted butter over entire dish to ensure cake is moist.
Bake in preheated oven for 50 - 60 minutes until golden brown and set. Cool before serving. Halfway during cooling time, take a knife and go between the baking dish and the cake to loosen it up on the sides.