12 inch Whoopee Pies
2 3/4 Cup Flour
2 Tbl Buttermilk Powder *
1 Tsp Baking Powder
1 Tsp Salt
1/2 Cup Cocoa Powder (types of cocoa)
1 1/2 Cups Sugar
1 Tsp Baking Soda
1   Cup Hot Water
  1/2 Cup Milk
1/2 Cup Shortening (same as 8 Tbl) (not Hi Ratio)
2 Egg yokes
1 Tsp Vanilla
 
 
* For real Buttermilk, leave off buttermilk powder and 1/2 cup hot water,  use 1/2 cup Buttermilk.  
If not using buttermilk, sub 1/2 cup milk with 1 tsp vinegar mixed for buttermilk powder and 1/2 cup liquid.
 
Blend Flour and Buttermilk powder before starting.
Mix  all dry.  Then add rest and beat well.  Should be like pancake batter.
Add water as needed. 
Pour half on parchment paper on metal sheet or pizza pan, 
make mound of about 8-9 inch diameter.  Makes 2 cookies
 
Bake 350 for 20-35 Minutes. Check with toothpick for clean test.
Heavy steel pans 18-25, others vary. Do not use silicone pans, will not cook as well.

Filling-

2 Egg Whites
3/4 Cups Hi Ratio Shortening (same as 12 Tbl) **
3 Cups Powdered Sugar
1/8 Tsp Salt
1/2 Tsp Vanilla
  2 TBL Milk - add enough to make smooth and fluffy
 
 
** Sub peanut butter or unsalted butter for 1/2 cup of shortening, if desired
** Add half cup shredded coconut for a change
 
** Hi Ratio shortening is used by bakers and is fluffier and reduces grease taste.
 
Mix on high for 15 minutes until smooth, DO NOT SHORT TIME THIS!!!
Add milk to reach your choice of filling thickness.
 
After outsides are cool, spoon filling between two above cookies

Cooking time varies by thickness of batter, thick may be done in 8 minutes, thin may take 30 or more.

For more of a dome, chill batter for ten minutes before cooking.

Check on effects of cocoa types here