Preheat your oven to 350°F (175°C) and line two baking sheets with parchment paper.

In a large mixing bowl, cream together the softened butter, brown sugar, and granulated sugar until the mixture is light and fluffy (about 3-5 minutes).

Add the eggs one at a time, mixing well after each addition. Then stir in the vanilla extract.

In a separate bowl, sift together the flour, cocoa powder, baking soda, and salt. Gradually add the dry ingredients to the wet mixture and mix until just combined.

Fold in the chocolate chips gently to ensure they’re evenly distributed throughout the cookie dough.

Using a cookie scoop or spoon, drop heaping tablespoons of cookie dough onto the prepared baking sheets, spacing them about 2 inches apart.

Bake for 10-12 minutes or until the cookies are set but still soft in the center. They should have a slightly domed shape.

While the cookies are baking, prepare the toffee sauce. In a saucepan, melt the butter over medium heat, then whisk in the heavy cream and brown sugar. Stir until the sugar is dissolved and the sauce is smooth, about 4-5 minutes.

Remove the cookies from the oven and let them cool on the baking sheet for a few minutes before transferring them to a wire rack.

Drizzle the warm toffee sauce over the cookies or serve it on the side for dipping.