Classic Sachertorte

Prep

1. Heat oven to 350°F. Grease a 9-inch springform pan and line the bottom with parchment. Lightly grease the parchment. If you are worried about seepage, set the pan on a sheet pan or wrap the outside base in a single layer of foil.
2. Melt the 6 oz chocolate for the cake (microwave in short bursts or over a gentle bain-marie). Set aside to cool until just warm.

Make the batter

1. In a mixing bowl, beat the butter with 1/2 cup (100 g) of the sugar until fluffy, about 2 to 3 minutes. Beat in vanilla.
2. Add the egg yolks one at a time, beating well after each addition. Mix in the melted chocolate.
3. In a clean bowl, beat the egg whites with salt until foamy. Gradually add the remaining 1/4 cup (50 g) sugar and beat to glossy, medium-stiff peaks. They should stand up, but the tip can gently bend.
4. Fold 1/3 of the whites into the chocolate mixture to loosen it. Sift in the flour and fold gently. Fold in the remaining whites in 2 additions, stopping as soon as you do not see streaks.

Bake and cool

1. Scrape batter into the pan and smooth the top.
2. Bake 30 to 38 minutes, until the top springs back lightly and a toothpick comes out with moist crumbs, not wet batter.
3. Cool in the pan for 10 minutes, then remove the ring and cool completely on a rack.

Jam layer

1. Warm the apricot jam in a small saucepan over low heat, adding up to 1 tbsp water only if needed to make it brushable.
2. Strain the jam through a fine-mesh sieve for a smooth, classic finish.
3. Slice the cooled cake horizontally into 2 layers. Set the top layer aside.
4. Brush a thin, even layer of jam over the cut side of the bottom layer, then place the top layer back on.
5. Brush jam over the top and sides in a thin coat. Let it set for 15 minutes. This helps the glaze go on smoothly.

Chocolate glaze

1. Set the jam-coated cake on a wire rack over a sheet pan.
2. In a small saucepan, heat heavy cream and sugar until steaming and the sugar dissolves, but not boiling hard.
3. Remove from heat, add the chopped chocolate, and let sit 1 minute. Stir until smooth, then stir in butter, corn syrup or honey (if using), and a pinch of salt.
4. Let glaze cool 3 to 5 minutes until it is thickened slightly but still very pourable.
5. Pour, then barely sweep: Pour glaze over the center of the cake and let it flow to the edges. Use an offset spatula only if needed to gently guide it toward any bare spots. Keep it minimal to avoid streaks.
6. Let the glaze set at room temperature for 1 to 2 hours, or refrigerate 30 to 45 minutes to firm it up faster.

Serve

1. Slice with a warm, dry knife for clean edges.
2. Serve with unsweetened or lightly sweetened whipped cream. That contrast is the whole point.