Process

For the brownies 

Preheat the oven to 350 degrees F (175 degrees C). Grease a 9×13-inch pan.

Mix sugar, flour, melted butter, eggs, cocoa powder, vanilla, baking powder, and salt in a large bowl until combined. Spread the batter into the prepared pan. Decorate with walnut halves.

Bake in the preheated oven until top is dry and edges have started to pull away from the sides of the pan, about 20 to 30 minutes; cool before slicing into squares.

Take the brioche buns and begin to grill

To assemble, take the brioche and top with the warm brownie, add a dollop of double cream and drizzle over sauce (we chose chocolate) add the burger lid and serve. We added a candid strawberry for presentation.