Preheat the oven to 350°F (175°C).

Grease a 9-inch round cake pan with butter and line the bottom with parchment paper.

In a double boiler, melt the chopped chocolate and butter together, stirring until smooth.

In a mixing bowl, whisk together the sugar and eggs until light and fluffy.

Pour the melted chocolate mixture into the egg mixture, stirring gently to combine.

Fold in the almond flour, vanilla extract, and salt until just combined.

Pour the batter into the prepared cake pan and smooth the top.

Bake for 35 to 40 minutes, until the cake has set but is still moist in the center.

Let the cake cool in the pan for about 10 minutes before transferring it to a wire rack.

Dust the cake with powdered sugar before serving.