Line 2-3 sheet pans with parchment paper. Set aside.
In a medium bowl, whisk together flour, cocoa, baking soda, and salt until well blended.
In the bowl of an electric mixer, using the paddle attachment, cream the butter and both sugars on medium speed until somewhat light. Add vanilla into a small bowl with the eggs, and add 1 egg at a time to the butter mixture, blending well before adding the remaining egg.
Add food coloring if using, and mix well.
On low speed, add approximately 1/3 of the dry ingredients to the egg and butter mixture, followed by ½ the buttermilk. Stop the machine and scrape down the sides of the bowl with a rubber spatula.
Add another 1/3 of the dry ingredients, followed by the remaining buttermilk.
Add remaining flour mixture and blend until just combined.
Spray a 2-ounce ice cream scooper with non-stick cooking spray. Fill scooper approximately 2/3 full with batter and drop batter onto sheet pans, spacing about 2 inches apart.
Bake for approximately 10 minutes, or until cakes feel spongy and spring back when gently touched with a finger. They will firm up as they cool.
Bake off remaining whoopie pies until all batter is used up.
Allow the whoopie pies to cool before assembling.
In the bowl of the Mountain Frosting, drizzle 2-3 tablespoons of jam and without mixing, using a clean 2-ounce scooper, place a scoop of frosting with streaks of jam in it onto one of the whoopie pie’s flat side. Cover with another whoopie pie flat-side down, pushing gently to adhere. Continue assembling whoopie pies and adding more jam to the frosting as needed.
Makes approximately 10-12 large whoopie pies
Raspberry Red Velvet Whoopie Pies - http://chefgailsokol.com/cakes-and-frostings/raspberry-red-velvet-whoopie-pies/