Preheat your oven to 350°F (175°C).

Line a baking sheet with parchment paper.

In a mixing bowl, cream together the softened butter, brown sugar, and granulated sugar until fluffy.

Add the egg and one teaspoon of vanilla extract, then beat until smooth.

In another bowl, whisk together the all-purpose flour, baking soda, and salt.

Slowly add the dry mixture to the wet ingredients, stirring until just combined.

Roll the dough into 1.5-inch balls and place them on the prepared baking sheet.

Make an indentation in the center of each dough ball.

Chill the cookie dough in the fridge for about 15 minutes.

In a small bowl, mix together the chopped pecans, brown sugar, corn syrup (or maple syrup), melted butter, half a teaspoon of vanilla extract, and a pinch of salt until well combined.

Remove the chilled dough from the fridge and place one teaspoon of the pecan filling into the center of each cookie.

Bake for about 10–12 minutes until the edges are golden and the filling is bubbly.

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