Preheat oven to 350 degrees. Combine cocoa and 2 cups boiling water in a large heatproof bowl, stirring until blended and smooth; cool completely. Beat butter with a mixer until creamy; gradually add sugar, beating until blended. Add eggs, 1 at a time, beating until blended after each addition. Combine flour and next 3 ingredients; add to butter mixture alternately with cocoa mixture, beginning and ending with flour mixture. Beat at low speed just until blended after each addition. Stir in chocolate extract.
Place paper baking cups in 2 (12-cup) muffin pans, and coat with cooking spray; spoon batter into cups, filling two-thirds full. Bake for 12 to 15 minutes. Cool in pans on wire racks 10 minutes; remove from pans, and cool completely.
To prepare frosting, beat butter at medium speed with an electric mixer until creamy. Gradually add powdered sugar, alternately with cream, beating at low speed until blended. Add salt and vanilla, beating until blended. Stir in crushed cookies until combined. Beat at high speed 2 minutes or until creamy. Makes 4 cups.
Fill each cupcake with Cookies and Cream Frosting. To fill cupcakes, insert the end of a wooden spoon or dowel into the center of the cupcake to make a hole. Fill a zip-top plastic freezer bag with filling or frosting. Use scissors or kitchen shears to snip about 1/4 inch from one corner of the bag; insert bag into the hole in the cupcake. Squeeze gently until filling comes to the top of each cupcake.
Frost each cupcake with Cookies and Cream Frosting using metal tip no. 12. Top each with 1 sandwich cookie or, if desired, crushed cookie pieces.