Preheat the oven to 350°F (175°C). Line a large baking sheet with parchment paper.
In a large bowl, whisk together the melted butter, granulated sugar, and light brown sugar until smooth and combined.
Add the eggs one at a time, whisking well after each addition. Stir in the vanilla extract.
In a separate bowl, whisk together the all-purpose flour, baking soda, and salt.
Gradually add the dry ingredients to the wet ingredients, stirring until just combined.
Fold in the semi-sweet chocolate chips and chopped pecans evenly throughout the dough.
Spread the dough evenly and thinly onto the prepared baking sheet, about 1/8 inch thick, smoothing the surface with a spatula.
Bake for 18-20 minutes or until the edges are golden brown and the center is set and crisp.
Remove from the oven and allow the cookie brittle to cool completely on the baking sheet. Once cooled, break into pieces.
Store the cookie brittle in an airtight container at room temperature for up to 1 week.