Prepare the Sponge Cake

1. Bring all ingredients to room temperature. Preheat the oven to 450°F. Grease a half-sheet pan and line it with parchment paper.
2. Place the 3 egg whites and cream of tartar in a clean mixing bowl fitted with a whisk attachment. Beat on medium speed until frothy, then gradually add the granulated sugar. Increase the speed to high and beat until soft peaks form. Transfer the whipped egg whites to a clean bowl and set aside.
3. Sift together the almond meal, confectioners’ sugar, salt, and Steve’s GF Cake Flour Blend.
4. Using the same mixing bowl, combine the sifted dry ingredients with the whole eggs. Beat on medium speed for 5–7 minutes, until the batter is thick and pale.
5. Gently fold one-third of the whipped egg whites into the almond batter. Add the melted butter and fold in the remaining egg whites, taking care not to deflate the mixture.
6. Pour the batter into the prepared pan and spread it carefully into a thin, even layer, reaching all the edges.
7. Bake for 5–7 minutes, until the top is lightly browned and the center springs back when gently pressed.
8. Immediately invert the cake onto a clean sheet of parchment paper. Starting from a long edge, roll the cake up tightly with the parchment inside. Allow it to cool completely in this position.

Make the Chocolate Italian Buttercream

1. Combine the water and sugar in a heavy-bottomed saucepan. Swirl the pan gently to moisten the sugar, but do not stir. Heat over medium heat, swirling occasionally.
2. Attach a thermometer to the saucepan. When the syrup reaches approximately 220°F, place the egg whites in a clean mixing bowl fitted with a whisk attachment and begin beating on low speed.
3. When the syrup reaches 243°F, carefully remove it from the heat and slowly pour it into the egg whites while the mixer runs on low speed. Avoid pouring the hot syrup directly onto the whisk.
4. Add the salt and increase the mixer speed to medium. Whisk for 5–10 minutes, until the mixture is thick and the bowl has cooled to room temperature.
5. With the mixer running on low to medium speed, add the softened butter a few tablespoons at a time. Allow each addition to incorporate before adding more.
6. Increase the speed to high and beat until the buttercream is smooth and creamy.
7. Add the vanilla extract and melted, cooled chocolate. Mix until fully combined. Set aside until ready to assemble the Yule log.

Make the Meringue Mushrooms

1. Preheat the oven to 225°F.
2. Place the egg whites and cream of tartar in a clean mixing bowl fitted with a whisk attachment. Beat on medium speed until frothy and white.
3. Gradually add the sugar and salt. Increase the speed to high and beat until the mixture forms almost stiff peaks.
4. Add the vanilla extract and continue beating until stiff, glossy peaks form.
5. Transfer the meringue to a piping bag fitted with a round tip. Pipe small mounds for the mushroom caps and separate upright pillars for the stems.
6. Lightly dust the mushroom caps with cocoa powder using a fine-mesh sieve.
7. Bake for 1 hour and 45 minutes to 2 hours, until the meringues are completely dry throughout but not browned.
8. Turn off the oven, remove the meringues, and allow them to cool completely.
9. Melt the chocolate and let it cool slightly. Trim the tips of the stems to create flat surfaces. Using a small pastry brush, apply a little melted chocolate to the underside of each cap and attach it to a stem. Allow the chocolate to set before handling.

Assemble and Decorate the Yule Log

1. Carefully unroll the cooled sponge cake. Spread approximately half of the chocolate buttercream evenly over the inside, leaving a ½-inch border along the bottom edge.
2. Roll the cake back up tightly, removing the parchment as you go. Position the seam underneath the cake.
3. Transfer the rolled cake to a serving platter. Cut off both ends, then position the cut pieces against the sides of the log to create the appearance of branches.
4. Spread the remaining buttercream over the entire log, including the branch pieces. Place the cake in the freezer for approximately 15 minutes, until the buttercream firms slightly.
5. Use a fork to draw lines through the buttercream, creating a bark-like texture. Adjust the pattern to resemble the natural grain of a tree.
6. Arrange the meringue mushrooms around the log. Dust with confectioners’ sugar to create a snowy finish, and add any additional decorations as desired.
7. Keep refrigerated until ready to serve. Allow the cake to sit briefly at room temperature before slicing for the best texture.

Baker’s Notes

• Work gently with the sponge: Folding the egg whites carefully helps preserve the cake’s light texture and makes it easier to roll.
• Roll while warm: Rolling the sponge immediately after baking helps it cool in the shape needed for assembly.
• Check the buttercream temperature: Allow the egg-white and sugar mixture to cool completely before adding the butter to help prevent the buttercream from becoming soupy.
• Make the decorations ahead: The meringue mushrooms can be prepared in advance and stored in an airtight container in a cool, dry place.
• Plan for several stages: The cake, buttercream, and mushrooms can be prepared separately before assembly to make decorating more manageable.