For the cookies:

1. Preheat the oven to 350F, and prepare 2 large baking sheets with parchment paper.
2. In a medium mixing bowl, whisk together the flour, sifted cornstarch, baking powder, baking soda, salt, cinnamon, and nutmeg, until well-combined. Set aside.
3. In a large mixing bowl, beat together the melted butter, brown sugar, white sugar, egg, egg yolk, and vanilla, until smooth, well-combined, and slightly aerated (about 1 minute of beating with a whisk).
4. Add in the dry ingredients to the wet, then use a spatula to fold the batter together until well-combined and smooth.
5. Using a small cookie scoop, scoop out the cookie dough onto the baking sheets (I did 9 per sheet), then place into the freezer for 25 minutes.
6. After 25 minutes, place the chilled cookies into the oven to bake for 13-14 minutes (I recommend baking in batches). When done, remove the cookies from the oven, then immediately press the back of a 1-tablespoon measuring spoon into the centre of each cookie to create a deep indent in each cookie. Transfer the cookies onto a wire rack to cool fully before filling with pecan pie filling.

For the pecan pie filling:

1. Add chopped pecans to one of the previously used baking sheets (the same parchment is fine) and place into oven for 3 minutes. Remove from oven, stir, then return to oven for another 3 minutes. Set aside.
2. In a medium saucepan over medium heat, add butter, brown sugar, and corn syrup (or maple syrup). Bring to a light boil, while stirring, and allow to boil for 1 minute. A
3. After 1 minute, add in the toasted pecans, stir, and continue to cook for another additional minute.
4. Finally, stir in the heavy cream, vanilla, cinnamon, nutmeg, and salt, then continue to cook for another 1-2 minutes, while stirring.
5. Remove from the heat, and allow the caramel to cool until it is still warm but thicker in texture.
6. When ready, scoop 1-2 tablespoons of the pecan pie filling into each cookie indent, and lightly press it in to each indent with the spoon. Allow the filling to cool and thicken more, about 20-30 minutes, before serving.