Making Ahead Instructions:
The best way to make a texas sheet cake ahead of time is to prepare and bake your cake the day before and make your frosting the day of. The frosting gets hard as it cools so adding it to the cake while still warm is the best way to get it on.
Prepare and bake your cake. Allow it to cool then cover with plastic wrap or foil and place in the fridge for up to 3 days. When you are ready to serve prepare frosting and pour onto cake. Allow frosting to cool then serve.