• Preheat the oven to 350°F. Spray a 9x13-inch baking pan with nonstick spray.
• In a bowl, using an electric hand mixer or in the bowl of a stand mixer, beat together the 15.25 ounce box lemon cake mix, 1 cup whole milk, ½ cup (1 stick) unsalted butter, melted and cooled, and 3 large eggs for 2 minutes on medium-high speed. Pour the batter into your prepared pan.
  
• Bake on the middle rack for about 20 to 25 minutes, or until a toothpick inserted in the center comes out clean. Let the cake cool for 30 minutes.
  

Filling:

• Using the back of a wooden spoon or a wide straw, poke holes all over the cake.
  
• Whisk together the 2 cups whole milk and 3.4 ounces INSTANT lemon pudding mix, then quickly pour the mixture over the cake, making sure to fill the holes.
  
• Refrigerate the cake for 1 hour to set.

Topping:

• Spread the 8 ounce tub whipped topping, thawed over the cake, then sprinkle the lemon zest from two lemons on top.