225g salted butter, plus more for buttering
225g dark chocolate (Pavlidou Hygeias)
1 cup brown sugar
1 cup white sugar
2 teaspoons mastic powder
1 cup flour
½ cup chopped walnuts
Butter a 33cm by 22cm baking dish and preheat the oven to 200 C. Melt the butter and chocolate in a bain marie, and set aside to cool. Beat the eggs, sugar and mastic in a bowl. Once mixed, beat in the melted chocolate. Stir in the flour and then add the walnuts. Pour the mix into the baking dish and bake for 35-40 minutes, or until the top is a bit crackly. Allow it to cool and serve.
If you want, you can sprinkle on top icing sugar or pour a bit of cream and add any berries of your choice!
*** Photo courtesy of Myrto Lazopoulou from Foodsnaps