Heat the oven to 350°F. Grease two 8-inch round cake pans and line each base using parchment paper. Stir the flour, baking powder, and salt together inside one bowl until evenly blended.

Beat the softened butter and granulated sugar until pale and fluffy. Add one egg at a time, mixing well after each addition. Blend in the vanilla extract for a smooth batter.

Add the dry mixture in three portions, alternating every addition using the buttermilk. Fold gently after the final addition until no dry streaks remain. Divide the batter evenly between both prepared pans.

Bake for about 28 to 32 minutes. Test the center using a wooden pick. Remove the pans after the pick comes out clean. Rest the cakes for 10 minutes before transferring them onto a wire rack to cool completely.

Place the chopped semi-sweet chocolate inside a heatproof bowl. Warm the heavy cream until steaming but not boiling, then pour it over the chocolate. Let it stand briefly before stirring until glossy and completely smooth. Allow the mixture to thicken slightly.

Position one cake layer onto a serving plate and spread a portion of the ganache across the surface. Add the second layer, then cover the top and sides using the remaining chocolate mixture. Leave the finished cake at room temperature until the coating sets before slicing and serving.