Start by preheating your oven to 350°F (175°C). This allows your cookies to bake evenly and achieve that perfect golden-brown color.

In a large mixing bowl, combine the packed brown sugar and white granulated sugar with softened butter and margarine. Using a hand mixer or stand mixer, beat them together until the mixture is light and fluffy. This step is crucial as it incorporates air into the dough, resulting in a lighter cookie.

Next, beat in the beaten egg, corn syrup, dark molasses, and vanilla extract. Make sure everything is well incorporated. It should feel like a rich and creamy mixture.

In a separate bowl, sift together the Dutch-process cocoa powder, all-purpose flour, baking soda, espresso powder, and salt. Sifting helps eliminate lumps and ensures your dry ingredients are mixed evenly.

Gradually add the dry mixture to the wet mixture. Stir gently until just combined. Overmixing can lead to tough cookies, and nobody wants that!

Fold in the milk chocolate chunks and toasted pecans. This is where the magic happens—your dough will start to look like a chocolate dream.

Scoop tablespoon-sized balls of dough onto ungreased baking sheets, keeping them spaced apart (about 2 inches). Bake in the preheated oven for about 10-12 minutes, until the edges are set but the centers are still soft.

Once baked, allow the cookies to cool on the baking sheet for about 5 minutes before transferring them to a wire rack. Patience is key! This cooling time allows them to firm up.