Preheat the oven to 180°C/gas 4 and line a 23cm square brownie tin with baking parchment.
Sift together the flour, baking powder and sea salt into a bowl.
Combine the soya yoghurt, vanilla seeds and honey in a large bowl. Add the light brown sugar and mix until well combined.
Gently fold the dry ingredients into the wet ingredients, then fold in the chopped dark chocolate.
Pour the batter into the prepared brownie pan and evenly spread over the pan with a spoon or spatula. Bake in the oven for 30–35 minutes, until the top of the blondie is firm and brown. Remove from the oven and let the blondie cool completely in the pan. Cut into 12 pieces and serve.