Preheat the oven to 350F/177C convection (325F/163C conventional) and line a large cookie sheet.
In a medium bowl, combine the melted butter with the brown sugar and egg. Whisk aggressively, for 2-3 minutes, until it lightens in color.
1/4 cup (56g) salted butter, 3/4 cup (150g) light brown sugar, 1 large egg
Add the flour, cocoa powder, baking powder and salt and use a rubber spatula to fold the dough just until the flour is almost combined.
3/4 cup (90g) all purpose flour, 1/3 cup (26g) unsweetened cocoa powder, 1 tsp baking powder, 1/4 tsp fine sea salt
Add the chopped chocolate and praline and fold until all the flour is combined and the chocolate and praline are evenly distributed.
1/3 cup (1 oz) semi-sweet chocolate, 2 Tbsp (1oz) pralined hazelnuts
Scoop the dough into 8 round balls with a 2 ounce cookie scoop. Roll them so they're smooth and then place five per pan.
Bake for about 6 minutes then remove the pan from the oven and bang it on the counter a few times so the cookies flatten a little. Quickly use a biscuit cutter (or anything round) to scoot the cookies back into a round shape and finish baking for another 6 minutes. Then bang them on the counter and scoot them with the biscuit cutter again. Allow them to cool to room temperature