Preheat the oven to 350°F (175°C). Grease the baking pan.

In a mixing bowl, whisk together melted butter, granulated sugar, and brown sugar until smooth.

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

In another bowl, combine flour, cocoa powder, and salt. Gradually add to the wet ingredients, mixing until just combined.

Fold in chocolate chips if using. Pour the brownie batter into the prepared baking pan.

In a separate bowl, mix together corn syrup, brown sugar, eggs, and vanilla extract until well combined.

Stir in chopped pecans.

Pour the pecan mixture over the brownie batter in the baking pan.

Bake in the preheated oven for 30-35 minutes, or until the topping is set and a toothpick inserted into the brownie portion comes out with a few moist crumbs.

Remove from the oven and sprinkle with sea salt. Allow to cool before cutting into squares.