Preheat the oven to 350°F (175°C). Grease and flour a 9×13 inch baking pan.
In a large mixing bowl, combine the lemon cake mix and lemon Jello powder.
Add the eggs, water, vegetable oil, sour cream, and vanilla extract to the dry ingredients.
Beat the mixture with an electric mixer on medium speed for 2 minutes until well blended.
Pour the batter evenly into the prepared baking pan.
Bake in the preheated oven for 28 to 32 minutes, or until a toothpick inserted into the center comes out clean.
Remove the cake from the oven and allow it to cool completely in the pan on a wire rack.
In a small bowl, whisk together the powdered sugar and fresh lemon juice until smooth to create a glaze.
Once the cake is cooled, drizzle the lemon glaze evenly over the top.
Let the glaze set for about 15 minutes before slicing and serving.