Beat butter and next 3 ingredients at medium speed with an electric mixer until creamy. Add eggs, 1 at a time, beating just until blended after each addition. Gradually add flour mixture, beating at low speed until blended. Stir in chocolate chunks.
Drop dough by heaping tablespoonfuls onto parchment paper-lined baking sheets.
Bake at 350° for 10 to 12 minutes or until puffy. Cool on baking sheets 2 minutes; remove to wire racks, and let cool 30 minutes or until completely cool. Spread cookies with Mocha Frosting. Dust evenly with powdered sugar, if desired.
Note: Dough may be frozen up to 1 month or refrigerated up to 2 days. Let stand at room temperature before baking as directed.