Store in an airtight container, in the fridge, for up to 5 days. You can freeze this, but it’s best to do so without the toppings. Do not garnish and this will last in the freezer for up to 3 months, in an airtight container.
I do not suggest doing this with one cake mix, but if you need to, use a 7x11 cake pan, reduce the cake ingredients by half, do not pour all of the jello over the cake as it’s too much, reduce the baking time to 25 minutes, and adjust the baking temperature to 340 degrees.
The red sanding sugar will melt into the whipped cream, so add it with that in mind.
Do not cook your cake any hotter than 325 degrees. This will cause it to cook unevenly and be a disaster.
Do not overmix your cake batter. This can cause it to rise too quickly and then fall, during the baking process, causing a crater in the middle of your cake. If this happens, you can fill in the crater with cool whip and no one will ever know.