Bake the cake and cool. Brush the surface of the cake the custard will come in contact with egg yolk Grill that surface cooking the yolk this will give you a good barrier. Make creme brûlée mix on stovetop over Bain Marie Cook out throurougly about 82 degrees c. Use agar agar or gelatin to gain a little extra strength in your custard, pass custard through A fine chinois Place cold cake into ring form lined with acetate , pour in custard mix and set in fridge min 6-8hours . Remove ring and peal of the acetate Make a caramel disc to place on top of brûlée cake or spun sugar or praline Hope this helps
