1cmilkwhole will make it the moistest, a substitute for water
4eggscalls for 3, an extra egg or just an extra yolk will make it more moist
1/2cbuttermelted, a substitute you can make for oil
Instructions
Pour dry mix into a bowl with the 3 other ingredients listed. You can use one or all of the substitutes for what is listed on the back of the box. Use a hand mixer on low to incorporate or whisk with your hand until dry mix is incorporated.
Preheat oven to 350 F and spray inside of 9x13" pan, pour in batter and bake about 30 minutes or until center springs back when touched with your finger gently.
** Other additions you can make are added 1 box of dry Jello pudding mix (as is, not made into pudding first) - this will make the outcome flatter and more dense but very very moist. 1/2 c mini chocolate chips can be added too.
To add more moisture to the top allow the cake to cool completely and add homemade or a tub of frosting to the top. Another option is to allow to cool for 20 minutes, poke with a large straw all over the top, melt a tub of frosting and pour the whole thing over the top so it seeps into the cake itself. (I would not use a box of pudding and this melted frosting idea together, it will be too sweet.)