White Chocolate Sacher Torte is an inventive riff on the classic European cake. White chocolate sponge cake is layered with rum-spiked apricot preserves and iced with a silky white chocolate glaze. Decorate the cake with white chocolate shavings for a beautiful presentation.
I had the idea to make a White Chocolate Sacher Torte kicking around for quite a while. I thought the combination of white chocolate and apricot would be tasty. But, for some reason, the recipe was languishing on my list of post ideas. I just kept putting it off.
Well, I guess I must have had some intuition of how difficult it would be to get the recipe right. I had to bake the white chocolate cake 5 times before I finally got a result I was happy with.
Of course the basis for this recipe is the my classic Sacher Torte. I knew that I couldn’t simply switch out the dark chocolate with white chocolate and call it a day. White chocolate is quite different than dark chocolate and it behaves differently in recipes.
Relative to dark chocolate, white chocolate has more fat and sugar. So, you guessed it, I reduced the amount of butter and sugar in the recipe to offset the white chocolate. I honestly thought I’d be pretty close to having a good working recipe with just those changes. Boy was I wrong.
The first cake, and the next three with variations in the amount of butter and sugar, baked up with a spongy top half and a gummy bottom half. I could see that the batter was separating before it set up. Because the cake was taking about 45 minutes to bake through, I thought if I could bake the cake faster the batter wouldn’t have time to separate before it set.
I figured two thin layers would bake faster than one thick cake. So I divided the batter between two pans, hoping that might do the trick. Nope, same gummy buttom, same spongy top. Clearly the white chocolate was affecting the batter beyond just the fat and sugar. Back to the drawing board.
Have you ever made one of those “magic cakes”? They’re made with a very thin batter with egg whites folded in. When you bake a “magic cake” the egg whites float to the top and bake into a spongy layer and the other ingredients sink and bake into a custardy bottom layer.
My cake was doing almost the same thing. I was using the same amount of flour and eggs as I did for my dark chocolate Sacher Torte. So why wasn’t the white chocolate batter setting fast enough?
Unlike dark chocolate, white chocolate is not acidic. In cake batter, an acidic ingredient will help the proteins to set more quickly. Maybe in a more acidic dark chocolate batter the eggs are able to set more quickly, so the batter doesn’t separate.
For my 5th test I reduced the number of eggs in the white chocolate batter. Fewer eggs means less liquid and protein in the batter. I also slightly increased the amount of flour (more starch) to help the batter gel before it could separate. While I was at it, I brought the sugar level back to the original amount to tenderize the slightly rubbery crumb on the cake.
Finally, that did the trick. The new cake is super moist and tender with a distinctly white chocolate flavor. Now it was time to work on the glaze.
I didn’t really change the ingredients of the glaze so much as I changed how they are mixed. If you’ve ever worked with melted white chocolate you know it can be a bit fussy. It has a tendency to seize up pretty easily. The first time I made the glaze the same way I make the dark chocolate glaze. I started by melting the white chocolate with the butter.
Arg, as soon as I stirred the melted white chocolate and butter the whole bowl seized up. I added the corn syrup and it was still lumpy and clumpy. I tried adding a little hot water and that improved the texture. But I needed to rethink how I mixed the glaze.
So I melted the chocolate separately from the other ingredients then mixed it all together. Yea! Now I had a perfectly smooth glaze that set to exactly the right texture on the cake.
It only took about 3 pounds of white chocolate, several dozen eggs and many, many hours, but I can finally cross White Chocolate Sacher Torte off my “to do” list.
- 1 1/2 cups (6.75 oz, 189g) cake flour
- 1/2 teaspoon baking powder
- 1/4 teaspoon table salt
- 3/4 cup (6 oz, 168g) unsalted butter, room temperature
- 1 cup (8 oz, 225g) granulated sugar, divided
- 6 large eggs, separated, room temperature
- 2 teaspoons vanilla
- 6 oz (170g) white chocolate, melted
- 1 1/2 cups (18oz, 510g) apricot preserves
- 1/4 cup (2 oz, 60 ml) dark rum
- 8 oz (225g) white chocolate, chopped
- 1 stick (4 oz, 112g) unsalted butter
- 2 tablespoons (1 oz, 28g) hot water
- 2 tablespoons (1.4 oz, 40g) corn syrup
- White chocolate for decoration
- Preheat the oven to 350°F. Line the bottom of two 9 inch cake pan with parchment paper, or butter and flour the bottom of the pans. You don't need to butter/flour the sides of the pans.
- Sift together the flour, baking powder and salt, set aside.
- Cream the butter and 3/4 cup of the granulated sugar until light and aerated. Add the egg yolks and vanilla, mix until combined. Mix in the sifted dry ingredients, don't over mix. Whisk the white chocolate into the batter.
- Whip the egg whites to soft peak. Slowly add the remaining 1/4 cup of sugar and whip to full peak. Fold the egg whites into the batter in 3rds, mixing until there are no streaks of egg white visible.
- Divide the batter between the prepared pans and bake until the middle of the cake springs back when pressed or a toothpick inserted into the middle comes out clean, about 20-25 minutes.
- Cool the cakes for 10 minutes in the pan then turn out onto a cooling rack until completely cooled (see note).
- Stir the rum into the apricot preserves.
- Using a serrated knife trim the top of the cakes so they are flat. Place one layer onto a cardboard cake round (it makes handling the cake easier). Spread 3/4 of the apricot mixture onto the bottom layer and place the other layer onto the cake.
- Strain the remaining apricot preserves into a clean bowl to remove the chunky bits of fruit. Ice the top and sides of the cake with the remaining apricot preserves. Place the cake in the freezer for at least 30 minutes while you make the glaze.
- Microwave the white chocolate in 15 second increments until melted. In a separate bowl, melt the butter with the hot water and corn syrup. Stir the warm butter mixture into the melted white chocolate until it's smooth.
- Remove the cake from the freezer and set it on a cooling rack set over a clean sheet pan. (If you are using a cardboard cake circle trim the excess so the board is the same size as the cake.) Starting at the center of the cake, pour the glaze all at once over the cold cake. Use a small spatula to spread the glaze over the top and let it fall over the sides of the cake. Use the spatula to fill in any gaps on the sides. You must work quickly before the glaze begins to set.
- For the traditional design, pipe the word "Sacher" onto the cake using melted white chocolate. Use a potato peeler to make shavings from a bar of white chocolate. Sprinkle the shavings around the top edge of the cake. Allow the glaze to set completely before moving the cake to a serving platter.
- Store and serve at room temperature. The assembled cake will improve for a day or two after being iced as the apricot preserves absorb into the cake.
The layers can be baked a day or two before assembly, or can be made several weeks ahead and frozen.
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