Whisk the melted butter, dark brown sugar, and vanilla sugar in a bowl. Whisk in the whole egg until the mixture is smooth.
Stir in the spelt flour, 1/3 packet of baking powder, baking soda, and salt until a soft dough forms. Gently fold in the dark chocolate chips.
Divide the dough into 5 or 6 round balls. Place them tightly next to each other in a small, greased oven-safe dish so they are touching.
Bake at 180°C (356°F) for 12 to 14 minutes. The edges should be golden, while the center stays soft and scoopable. Let it cool for 5 minutes before serving.