White Christmas Cake with White Chocolate Buttercream

Make the sugared cranberries

1. In a medium saucepan over medium-high heat, combine the water, 3/4 cup (150 g) of the granulated sugar, and the salt. Bring to a gentle boil and turn the heat down to medium; let simmer until the mixture is reduced slightly, about 5 minutes. Pour the vanilla into the sugar liquid and stir to combine.
2. Pour the liquid into a medium-size container. Add the cranberries to the sugar liquid, cover and refrigerate, and let them soak for at least 8 hours and up to 24 hours.
3. After the cranberries have soaked, place the remaining 1/2 cup (100 g) of granulated sugar in a bowl and line a sheet pan with parchment paper. Drain the cranberries and roll them in the bowl of sugar to coat. Place the coated cranberries on the sheet pan and let them dry, at least 1 hour. Cranberries can be stored in an airtight container in the refrigerator for up to 2 days.

Make the cake

1. Preheat the oven to 350°F (180°C).
2. Butter and flour three 8-by-2 inch (20-by-5 cm) round cake pans and line the bottoms with parchment paper.
3. In a medium bowl or liquid measuring cup, whisk together the milk, egg whites, crème frâiche, and vanilla.
4. In the bowl of a stand mixer fitted with the paddle attachment, combine the flour, granulated sugar, baking powder, and salt. With the mixer running on low speed, add the butter one piece at a time, beating until the mixture resembles coarse sand, 3 to 4 minutes.
5. With the mixer still running on low speed, slowly add a little more than half of the wet ingredients. Increase the speed to medium and beat until the ingredients are incorporated, about 30 seconds. Return the mixer to low speed and add the rest of the wet ingredients, mixing until just combined.
6. Increase the speed to medium and beat for 20 seconds (the batter may still look a little bumpy). Scrape down the sides and bottom of the bowl and use a spatula to mix the batter a few more times.
7. Divvy the batter between the prepared pans and smooth the tops. Tap the pans gently on the counter, two times each, to help get rid of any bubbles.
8. Bake, rotating the pans halfway through, until the cakes are golden brown and a wooden skewer or toothpick inserted into the centers come out with a faint bit of crumbs, or a finger gently pressed into the top leaves a slight indentation, 28 to 30 minutes.
9. Transfer the pans to a wire rack and let cool for 30 minutes. Turn the cakes out onto the rack, remove the parchment paper, and let cool completely. Once cool, the cakes can be frosted or wrapped in plastic wrap and refrigerated overnight or for up to 1 week.

Make the white chocolate buttercream

1. Pour 1 inch (2.5 cm) of water into a medium saucepan and bring it to a simmer over medium heat.
2. In a heatproof bowl set over the simmering water, melt the white chocolate, being careful not to let the water touch the bottom of the bowl. Stir constantly until just melted then remove from the saucepan and let cool.
3. In the bowl of a stand mixer fitted with the paddle attachment, beat the butter on medium speed until light yellow and creamy, about 3 minutes.
4. Add the corn syrup and salt and mix on medium speed until combined. Reduce the speed to low and gradually add the confectioners’ sugar, then increase the speed to medium and beat until smooth and creamy, stopping to scrape down the sides of the bowl as necessary, 2 to 3 minutes.
5. Reduce the mixer speed to low, add the cooled white chocolate and beat until completely combined. Pour in the heavy cream and vanilla and mix until combined.

Assemble the cake

1. Place one layer of cake on a turntable or serving plate. Use an offset spatula to spread the top evenly with 3 tablespoons of cranberry jam. Place the second layer on top and frost with another 3 tablespoons of the jam, then place the final layer on top and evenly coat the entire cake with the buttercream.
2. The cake can be stored, covered, in the refrigerator for 24 hours. Let the cake come to room temperature and top with the cranberries just before serving.