Preheat the oven to 180°C/350°F.
Heat a thick-bottomed skillet on medium heat. Add the butter and cook until brown, it will have a nutty aroma.
In a medium bowl, melt the dark chocolate in a microwave.
Pour the brown butter over the chocolate. Stir together until the mixture is smooth.
Whisk in the granulated sugar and vanilla paste.
Add eggs one at a time, whisking well after each addition.
Sift in the deZaan cocoa powder and whisk until just combined.
Pour the batter into a round baking pan.
Bake until a wooden pick inserted in the center of the cake comes out clean, about 35-40 minutes.
Unmold and dust cake with deZaan cocoa powder and decorate with fresh berries and edible flowers.