In a pan, melt butter and chocolate. Take it off from the stove and incorporate the baking powder and the flour.
Preheat the oven 350°F (180°C ).
In a bowl, beat the egg yolks with the maple sugar and white sugar until the mixture whitened. Add it to the chocolate.
In another bowl, beat the egg white with the salt until fluffy and firm. Add to the chocolate.
Pour in a greased and floured cake pan of 10-12 inches (26 à 28 cm de diamètre).
Cook for 30 min. Cake is ready when inside is dry. Cool down before unmolding.