1. Preheat oven to 350ºF and line a rimmed baking sheet with parchment paper. Using an electric mixer on medium-high speed, cream together butter, confectioners' sugar and vanilla until smooth. Stir in flour and salt just until a dough forms. Fold in chocolate chips and toffee bits.
2. Using your hands, roll dough into 1-inch balls. Place on prepared baking sheet, 1 inch apart, pressing down lightly on each one with a moistened palm.
3. Bake until cookies are firm and just golden around edges, 12 to 14 minutes. Place baking sheet on a wire rack for 5 minutes, then transfer cookies to rack to cool. Repeat with remaining dough. Store cookies in an airtight container at room temperature for up to 3 days.