Tishe,
This is my sister-in-law's recipe for the Texas Sheet cake she brought to our grandson's shower. Enjoy!

Mix and set aside:
2 cups flour
2 cups sugar
1/2 tsp salt
1/2 tsp allspice
2 tsp cinnamon

Boil:
1 cup water
3 or 4 Tbls powdered cocoa (unsweetened)
1 stick butter
1/2 cup oil

Pour over dry ingred. and blend well.
Add:
2 eggs
1/2 cup buttermilk*
1 tsp soda
1 tsp vanilla

Batter is thin. Pour into cookie sheet. Bake at 400 for 20 min or until toothpick comes out clean.

Frosting:
boil: 1 stick butter, 3 or 4 Tbl cocoa, 6 Tbls milk.
pour over 1 lbs powder sugar and beat - add 1 tsp vanilla

Spread over cake while still warm.

*buttermilk: I never buy buttermilk, so here's how to cheat: pour milk into 1/2 C measure cup but not completely full. Add a tablespoon or more of vinegar to sour the milk.