Preheat the oven to 350F , Butter and Flour an 8-inch round  fluted pan with a removable bottom , tapping out the excess.

Whisk the egg whites with the granulated sugar until medium-stiff peaks form .

Meanwhile , fill a medium sauce pan with an inch of water and bring to a simmer . Combine the chocolate and butter in a heatproof bowl and set over the simmering water . Melt , stirring occasionally . Remove the bowl from the saucepan .

Beat I yolk into the chocolate mixture to temper it . Beat in the remaining yolks , then beat in the confectioners sugar , almond flour and all purpose flour until well mix .

Add the third of the whipped whites and beat well to loosen the chocolate mixture . Gently fold in the remaining whites just until combined . Pour into the prepared pan and gently spread evenly .

 Bake until puffed and a knife comes out almost clean, about 17 minutes (The hot chocolate will continue to bake evn outside the oven)  Let cool in the pan on a wire rack for 10 minutes (not completely) , then invert onto the rack . Carefully flip the cake right side up . Let cool completely . Dust with cocoa powder .