Step 1

Preheat oven to 350 degrees F. Grease a 9-inch square baking pan; set aside.

Step 2

Make the Filling: Remove ⅔ cup of the cake mix and place in a medium bowl. Add the melted butter, brown sugar, cinnamon, and chopped pecans, mixing with a spoon or spatula to thoroughly combine.

Step 3

In a large bowl, combine the remaining cake mix, eggs, and sour cream until completely combined.

Step 4

Pour half of the wet batter into the prepared pan, then sprinkle evenly with half of the filling.

Step 5

Pour the remaining batter over top and smooth it into an even layer. Sprinkle the remaining filling mixture over the top of the batter.

Step 6

Bake for 45 minutes to 1 hour, or until a toothpick or thin skewer inserted into the center comes out clean. Allow to cool for at least 15 minutes before serving to serve warm; it can also be served at room temperature.