1In medium bowl, mix flour, cocoa and salt. In large bowl, beat 1 cup butter and 1 cup powdered sugar with electric mixer on medium speed until light and fluffy. Gradually beat in chocolate. On medium-low speed, beat in flour mixture until blended. Cover with plastic wrap and refrigerate 30 minutes.
2Heat oven to 325°F. Shape dough into 3/4-inch balls. On ungreased cookie sheets, place balls 2 inches apart. Bake 12 to 14 minutes or until set. Remove from cookie sheets to cooling racks. Cool completely, about 30 minutes.
3In large bowl, beat cream cheese and 1/4 cup butter with electric mixer on medium speed until light and fluffy. On medium-low speed, gradually add 1 3/4 cups powdered sugar and peppermint extract. For each sandwich cookie, spread 1 rounded teaspoon filling on bottom of 1 cookie. Top with second cookie, bottom side down. Roll edges in crushed peppermint candy.