- Preheat oven to 180C. Butter and flour a 9x9x2-inch metal baking pan.
- Whisk flour, baking powder, and salt in a large bowl. Combine ½ cup chocolate chips and butter in a large stainless-steel bowl.
- Set bowl over a saucepan of simmering water and stir until chocolate and butter are melted and smooth. Remove bowl from heat; whisk in sugar, cocoa powder, vanilla, and yoghurt.
- Fold wet ingredients into dry ingredients.
- Fold in remaining ½ cup chocolate chips. Pour mixture into prepared pan.
- Bake until a tester inserted into center of brownie comes out with a few moist crumbs attached, 25-28 minutes. Let brownie cool completely.
- Cut into squares with a sharp knife. Or serve slightly warm with Kefalos Vanilla Bean or Hazelnut Ice Cream.