Start by preheating your oven to 350°F (175°C). This ensures that your cookies bake evenly and achieve that perfect golden color.
Line a large baking sheet with parchment paper to prevent sticking and to facilitate easy cleanup.
In a large mixing bowl, use an electric mixer to cream together the unsalted butter, brown sugar, and granulated sugar. Beat until the mixture is light and fluffy, about 2-3 minutes.
Add in the large eggs one at a time, mixing well after each addition. Then, stir in the vanilla extract until combined.
In a separate bowl, whisk together the all-purpose flour, baking powder, salt, and instant chocolate pudding mix.
Gradually add the dry mixture to the wet ingredients, mixing until just combined. Be careful not to overmix, as this can lead to tough cookies.
Gently fold in the bittersweet chocolate chips, semi-sweet chocolate chips, Heath toffee bits, and toasted pecans (if using) until evenly distributed throughout the dough.
Using a cookie scoop, portion out generous amounts of dough onto the prepared baking sheet, leaving ample space between each cookie to allow for spreading.
Bake in the preheated oven for 10-12 minutes, or until the edges are lightly golden. The centers may look slightly underbaked; this is perfect as they will continue to cook on the baking sheet.
Remove the cookies from the oven and let them cool on the baking sheet for about 5 minutes before transferring them to a wire rack to cool completely. Enjoy these delicious Giant Chocolate Toffee Pecan Cookies warm or at room temperature!