Gluten Free Bûche de Noël

Preheat your oven to 350°F.

Grease 15 x 10 inch rimmed baking sheet. Line it with unbleached parchment paper, then grease again.

Sprinkle some extra flour on the greased paper, and tap it around to evenly distribute it. Set the pan aside.

In a large bowl, place the flour, xanthan gum, cornstarch, baking powder, baking soda, salt and sugar, and whisk to combine.

Add the butter, eggs, vanilla and 3 tablespoons water, mixing well after each addition.

The batter should be thin and easily pourable. If necessary to achieve the proper consistency, add more water by the tablespoon and mix again.

Pour the batter into the prepared pan, and shake it gently back and forth and side to side so that the batter is in an even layer.

Smack on the counter to break any trapped bubbles.

Place the pan in the center of the preheated oven and bake for about 15 minutes, or until top of cake springs back when touched.

While the cake is baking, spread a tea towel out flat on the counter, and sprinkle it liberally with confectioners’ sugar.

Once the cake is done, turn it immediately onto the prepared towel.

Carefully peel off the paper, and place a short edge of the towel over the short edge of the cake.

Roll the cake and towel together tightly, starting with narrow end and rolling away from your body.

Transfer the rolled cake and towel onto a wire rack to cool completely.

While the cake is cooling, make the filling. In the bowl of a stand mixer fitted with the paddle attachment, beat the butter and shortening until light and fluffy.

Place the chopped chocolate in a small, microwave-safe bowl. Microwave for 45 seconds at a time on 60% power, stirring well in between microwaving, until melted and smooth.

Pour the chocolate mixture into the mixer, and beat to combine well.

Add 2 1/2 cups confectioner’s sugar to the mixer, and mix until well-combined.

With the mixer on low speed, add the corn syrup.

The frosting should be smooth but thick enough to hold its shape when scooped with a spoon. If it is too thin, add more confectioners’ sugar by the tablespoon until it reaches the proper consistency.

Set the filling aside.

Place the chopped chocolate in a medium-sized heat-safe bowl.

Place the cream in a small, heavy-bottom saucepan and place over a medium flame until the cream just begins to simmer.

Pour the cream over the top of the chopped chocolate and allow it to sit undisturbed for a minute or so to melt the chocolate.

Stir until smooth, and set the ganache aside to thicken as it cools.

Once the cake is cool, carefully unroll it.

Remove the towel, and spread the buttercream all over the cake, leaving a 1½ inch clean border all around.

Carefully reroll the cake tightly.

Wrap it securely in plastic wrap and place in the freezer until firm, about 15 minutes.

Remove the cake from the freezer, unwrap the plastic wrap and slice off the very end of both sides of the cake to create clean edges.

Place the cake, seam side down, on a wire rack above a clean rimmed baking sheet.

Pour the ganache evenly over the cake, and spread it into an even layer.

With a small offset spatula or butter knife, create lines along the cake that run along the length of the cake to resemble the bark of a tree.

If the ganache does not hold its shape in a pattern, place the cake in the refrigerator to cool a bit.

Place the decorated cake in the refrigerator to set.

Allow to sit at room temperature for 30 minutes before slicing thickly to serve.