5 (1.4-ounce)barschocolate-covered English toffee, such as Heath, coarsely chopped
Whisk flour, baking powder and salt together in small bowl. Place chocolate and butter in a microwave-safe bowl and heat on 50% power for two minutes. Stir and continue microwaving in one minute (50% power) increments, stirring after each minute, until chocolate and butter are melted and combined. Cool mixture to lukewarm.
Using electric mixer, beat sugar and eggs in bowl until thick, about 3 minutes. Beat in chocolate mixture and vanilla.
Stir in flour mixture, then chopped toffee bars. Chill batter until firm, about 45 minutes.
Preheat oven to 350°F. Line 2 large baking sheets with parchment or waxed paper. Drop batter by rounded tablespoonfuls onto sheets, spacing two inches apart.
Bake just until tops are dry and cracked but cookies are still soft to touch, about 12 to 15 minutes. (Can be made 2 days ahead. Store airtight at room temperature.)
Chocolate: do not substitute chocolate chips since they melt differently; I use Baker’s baking chocolate that is usually found above the chocolate chips in the baking aisle.