Sift the cake mix into your mixing bowl. Add all of the other ingredients: instant vanilla pudding mix, eggs, brown sugar, flour, sour cream, pineapple juice, vegetable oil, and vanilla extract.
Mix at medium speed for one minute. Scrape the sides and bottom of the bowl and mix one more minute.
Pour or scoop the batter into the sheet cake pan, covering the brown sugar, pineapple rings, and cherries.
Bake for 40-45 minutes or until a skewer or until cake springs back when lightly touched and a toothpick inserted into the cake comes out clean or with just a few crumbs attached. Baking times may vary- check your cake for doneness as it approaches the 35 minute mark.
Cool the cake in the pan for 10 minutes before inverting it onto your cake platter or cake board. If your cake bakes up with a dome in the center, it is a good idea to minimize it- either by gently slicing away the dome with a serrated knife, or gently pressing it down using a clean dish towel.
Next, place the cake platter on top of the the cake pan, and carefully flip it all as one (using dish towels or oven mitts to protect your hands from the heat.)
Leave the sheet cake pan upside down for a minute or two to give the the glaze a little more time to drip down.
Serve warm or cool. If not serving right away, it is best to refrigerate and then remove from the refrigerator 2-3 of hours before serving. This cake tastes best when at least room temperature or warm. If served when cold, the texture will not be the same (because of the butter in the recipe.)