Begin by making your chocolate-covered toffee. Chop it into bite-sized pieces and dip each piece in melted semisweet and milk chocolate. Lay the coated toffee pieces on a parchment paper-lined tray to set.

Preheat your oven to 375°F (190°C) and line baking sheets with parchment paper.

In a medium bowl, whisk together the flour, cocoa powder, baking powder, baking soda, and salt until combined.

In a large mixing bowl, beat softened butter with brown and granulated sugar until light and fluffy, about 2-3 minutes. Add the egg and vanilla extract, mixing until just combined.

Gradually incorporate the dry ingredients into the wet mixture, folding gently with a spatula. Fold in chocolate-covered toffee pieces evenly.

Chill the dough for 30 minutes if desired to enhance the flavor.

Scoop approximately 4.5 ounces of dough, roll into balls, and place on prepared baking sheets.

Bake at 375°F for 10 minutes, then reduce to 350°F (180°C) for an additional 3-5 minutes.

Allow the cookies to cool on the baking tray for 3 minutes before transferring to a wire rack to cool completely.