The fluffy, caramel provides buttery relief from the dense, chocolaty crumb of the cookie - the kind that packs to the back of your palate and begs for a glass of milk.

• 1 3/4 cups all-purpose flour
• 3/4 cup cocoa powder
• 1 1/2 teaspoons baking soda
• 1/2 teaspoon salt
• 1/2 cup butter, softened
• 1/2 cup white sugar
• 1/2 cup packed brown sugar
• 1 cup milk
• 1 egg
• 1 teaspoon vanilla extract
• Salted Caramel Buttercream (below)

1. Preheat oven to 375 degrees. Grease two large cookie sheets, or line with parchment paper.
2. Whisk together the flour, cocoa powder, baking soda and salt.
3. In the bowl of a standing mixer, cream the butter and sugars together, 2-3 minutes. Add the egg and continue beating until fluffy, 1-2 minutes longer. Beat in milk and vanilla extract. Finally, beat in flour mixture to combine.
4. Drop by heaping tablespoons onto prepared cookie sheets (you should get 12-14 cookies).
5. Bake for 10-14 minutes, until top springs back when touched.
6. Cool completely. Spoon a heaping tablespoon of frosting on the flat half of one cookie, then top with another cookie. Repeat.

• 1/2 cup sugar, divided
• 2 tbsp water
• 2 tbsp + 2 tsp (40 mL) cream
• 2 egg whites
• pinch of salt
• 1/2 cup butter, softened
• 1/2 tsp vanilla extract

1. Put 1/4 cup of sugar and water in saucepan over medium-high heat. Do not stir of you will get sugar crystals, but you can swirl the saucepan gently. It will bubble itself into a deep amber. Remove immediately from heat and add cream (careful - it will bubble up furiously). Stir until smooth and set aside.
2. Put the egg whites, salt, and 1/4 cup sugar in a heatproof bowl over a pot of simmering water. Whisk until sugar dissolves and mixture reaches 140 degrees. Transfer to bowl of standing mixer.
3. Beat on high until stiff peaks form. Add butter a bit at a time, and continue beating on medium. Reduce speed to low, add vanilla extract, and then caramel (you may need to gently rewarm the caramel in the microwave for 10 seconds at a time until it is workable but not burning hot). Beat for 4-5 minutes.

From http://www.foodess.com/2009/02/whoopie-pies-with-salted-caramel-buttercream/