Preheat the oven to 350°F (175°C).

In a double boiler, melt the chopped semisweet chocolate and unsalted butter together over simmering water until smooth, about 5 minutes.

In a separate bowl, whisk the granulated sugar and eggs until pale and frothy, about 3-5 minutes.

Gradually whisk the melted chocolate and butter into the sugar and egg mixture until well combined.

Stir in the vanilla extract, all-purpose flour, and salt until just combined, being careful not to overmix.

Grease the 9-inch round cake pan and pour in the batter, smoothing the surface with a spatula.

Bake at 350°F (175°C) for 25 to 30 minutes until the edges are set but the center remains slightly soft.

Let the torte cool in the pan for 10 minutes, then transfer to a cooling rack to cool completely.