Place the pecan nuts in a food processor and process until you have a creamy pecan nut butter. Set aside.
Add the butter, sugar, egg, and salt into your kitchen machine and whisk for 2 minutes at high speed until well combined.
Add one tablespoon of vanilla extract and the pecan nut butter and whisk for another minute.
Chopp the chocolate into small cubes and add it with the flour and baking powder to the mixture.
Stir until everything is evenly combined.
Cover the bowl with a plastic wrap and refrigerate for one hour.
Preheat your oven to 180°C/350°F (conventional) and line one baking sheet with baking paper.
To make the cookies, work with two tablespoons. Take one tablespoon of the cookie dough and place it with the other tablespoon carefully on the baking paper. You don't need to form it; they will flatten themselves once in the oven. Do this until no cookie mixture is left. Make sure to leave some space between the cookies as they will flatten once in the oven.
Bake your cookies in the middle of the oven for 15 minutes.
Take them out, let them cool down for 2 minutes on your baking sheet until you transfer them to a cooling rack. As they are very soft when you take them out of the oven, they could easily break apart if you don't leave them to cool down for 2 minutes on the baking sheet.
Eat your cookies still warm and store them in a jar for a few days.
If you don't have a food processor at home to make pecan nut butter and cannot buy it in your supermarket, you can substitute it with another nut butter.