With the rack in the middle position, preheat the oven to 400°F (200 °C). Line a baking sheet with parchment paper.
In a bowl, combine the flour, salt and baking powder. Set aside.
In another bowl, cream the butter and brown sugar with an electric mixer. Add the egg and vanilla and beat until smooth. With the mixer at low speed or or using a wooden spoon, stir in the dry ingredients and the chocolate.
Using a 2-tablespoon (30 ml) ice cream scoop, form balls of cookie dough and place them on the baking sheet, leaving about 2 inches (5 cm) between each cookie. Flatten slightly with your fingertips.
Bake for about 8 minutes. Let cool on a wire rack.