Preheat your oven to 350°F (175°C). Grease a 9x13 inch baking pan with cooking spray or butter.

In a large mixing bowl, combine the yellow cake mix and vanilla pudding mix. Mix well to incorporate.

In another bowl, whisk together the sugar, sour cream, eggs, vegetable oil, and vanilla extract until smooth and well blended.

Gradually add the wet mixture into the dry ingredients, mixing continuously until the batter is smooth and free of lumps.

Pour the batter into the prepared baking pan and spread evenly with a spatula.

Bake in the preheated oven for 40-45 minutes. Check doneness by inserting a toothpick in the center—if it comes out clean, the cake is done.

Remove the cake from the oven and allow to cool in the pan for 10-15 minutes. Transfer to a cooling rack.

Dust the cooled cake with powdered sugar before serving for a sweet finishing touch.