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

In a medium bowl, whisk together the all-purpose flour, baking soda, and salt until combined.

In a large mixing bowl, cream the softened unsalted butter with brown sugar and granulated sugar until light and fluffy.

Add egg and vanilla extract to the mixture, and beat until smooth and fully incorporated.

Gradually fold the dry mixture into the wet mixture until just combined.

Melt some butter in a saucepan over low heat, stir in brown sugar and corn syrup, and simmer for 2-3 minutes.

Mix in chopped pecans and a splash of vanilla to create the filling.

Portion tablespoon-sized dough onto the baking sheet and create a well in the center to add a teaspoon of the pecan filling.

Bake for 10-12 minutes, until edges are golden brown and centers are just set.

Allow cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack.