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Lemon Bûche de Noël with Lemon Mascarpone Icing

Servings: 12

Ingredients

Lemon Jelly Roll Cake

  • 3/4 cup all purpose flour
  • 1 tsp baking powder
  • 1/2 tsp salt
  • 4 room temperature eggs separated
  • 1/4 c sugar to be added to the beaten egg yolks
  • 1/2 c sugar to be added to the soft peaked egg whites
  • 2 tbs lemon juice
  • 1 tsp vanilla
  • 2 tsp lemon zest
  • icing sugar and clean towel for rolling the cake

Lemon Soak

  • 1/2 c sugar
  • 1/3 c water
  • zest of 1/2 lemon
  • 1/4 c lemon juice OR 1/8 c lemon juice and 1/8 c rum, brandy, or other (non-creamed) spirit of choice

Lemon Cream Filling

  • 1 cup  whipping cream
  • 2-3 tbs lemon juice
  • 1/2 cup sifted icing sugar
  • zest of 1/2 lemon

Lemon Mascarpone Icing

  • 16 oz ~475 g Cold Mascarpone Cheese [2 of the small tubs]
  • 1 c icing sugar
  • 3 tbs lemon juice
  • 1 tsp vanilla
  • zest of 1/2 lemon if desired
  • 4-6 tbs milk or cream

Candied Lemon Slices

  • 1 lemon
  • Pot of Boiling Water
  • Ice Water Bath
  • 1+ c sugar
  • 1 c water

Make-Ahead Meringue Mushrooms

  • 2 egg whites room temperature
  • 1/8 tsp cream of tartar
  • 1/2 cup sugar
  • 1/4 cup white or semisweet chocolate pieces
  • lemon zest and/or icing sugar for dusting [optional]

Instructions

Lemon Jelly Roll & Assembly

  • Heat oven to 375.
  • Grease a 15x10x1 baking or jelly roll pan or spray it with baking spray.
  • Line it with a waxed or parchment paper rectangle cut 1/2 inch smaller than the pan (14×9).
  • Grease the paper or spray it with baking spray.
  • Sift flour, baking powder, and salt into a bowl or onto another sheet of waxed paper and set aside.
  • In a mixer, beat eggs yolks, lemon juice, and vanilla until thick and yellow.
  • Add the 1/4 cup sugar and beat on high until dissolved.
  • Add zest.
  • Pour mixture into a clean bowl and set aside.
  • Wash the mixing bowl and beaters.
  • Beat the egg whites on medium until soft peaks form.
  • Add the 1/2 c sugar by the tablespoon and beat until stiff peaks form.
  • Fold the reserved egg yolk mixture into the beaten egg white mixture quickly with the mixer or with a spatula.
  • Gently and quickly, fold in the flour mixture with a spatula.
  • Spread batter into the pan as evenly as possible.
  • Bake 12-15 minutes until center spring back when pressed lightly with a fingertip. [The cake may look a bit bubbly or even mountainous! No worries! It will flatten out with the folding, anyway!]
  • Immediately loosen the edges of the cake with a knife.
  • While the cake is still quite warm, Invert pan onto a clean towel dusted generously with icing sugar.
  • Peel off waxed paper.
  • Gently roll wider length of cake jelly roll style in towel. You want a long thin roll, not short and thick.
  • Cool rolled and wrapped cake completely on a wire rack [You can store the cake like this for up to one day or re-roll the cake in wax paper, wrap wax-paper rolled cake in foil and freeze for 2-3 weeks.]
  • Unroll your cake from the towel.
  • [Optional] Using a pastry or basting-style brush, spread the Lemon Soak generously onto the [inside] surface of the roll cake. [I only used about 1/16 of a cup.]
  • Spread the inside/top surface of the unrolled cake with the Lemon Cream.
  • Gently re-roll the cake.
  • Place the filled cake on a serving plate.
  • Cut a 1/2in-or-thicker slice(s) from the ends of the cake roll to use as knot(s) or trimmed limb(s) of cake. Or, if using as a jelly roll, skip to Step 29.
  • Use the Lemon Mascarpone Icing to attach these knots and limbs to the cake roll.
  • Frost the cake roll with the remaining Lemon Mascarpone Icing.
    You do not have to ice the open ends and open knots of the cake. This is a bit tricky, but can be done with a clean icing spreader.
  • If desired, use the tines of a fork or an icing spatula to make the icing look like realistic “bark.”
  • If desired, decorate with Make-Ahead Mushrooms, Candied Lemon Slices, and additional lemon zest.
  • Chill until 10-20 minutes before serving time.

Lemon Soak

  • Place the sugar and water in a small pan and heat until the sugar has dissolved completely.
  • You do not need to boil this.
  • Remove from heat.
  • Add juice and/or alcohol.

Lemon Cream

  • Combine all ingredients in a cold stand mixer or bowl and beat with cold beaters until stiff.

Lemon Mascarpone Icing

  • Beat the mascarpone, sugar, zest, vanilla, and lemon juice on high until incorporated.
  • Gradually add the milk or cream 1 tbs at a time until the icing becomes as spreadable as you would like.
  • You may also add additional icing sugar if desired.
  • Refrigerate until ready to use.

Candied Lemon Slices

  • Slice lemons into 10- 12 thin slices [use a mandoline if necessary].
  • Compost lemon seeds and top and tail of lemon.
  • Arrange a bowl of ice water on the counter.
  • In a pot of boiling water boil lemons for one minute.
  • Drain and place lemons in ice bath.
  • In a flat low pan, bring 1 c water and 1 c sugar to simmer to dissolve.
  • Reduce heat to medium low.
  • Drain lemon slices again.
  • Arrange lemon slices flat on pan in sugar syrup.
  • Simmer for 1 hour.
  • Remove slices to a parchment-lined rack or plate to cool.

Make-Ahead Meringue Mushrooms

  • Heat oven to 200.
  • Line two large cookie sheets with parchment.
  • Beat egg whites and cream of tartar at medium speed until soft peaks form.*
  • Increase speed and, one tablespoon at a time, sprinkle in the sugar until the sugar dissolves and the meringue forms stiff peaks. It will be thick and shiny, a cross between marshmallow fluff and taffy.
  • Attach a 1/2-inch round tip to a pastry bag or ziploc bag.
  • Fill the bag halfway with meringue and make an equal number of caps and stems, as described in the next two steps. 
  • For the mushroom caps, squeeze meringue into 1.5-in rounds, pulling off to the side to avoid pointy tips.
  • For the stems, hold pastry bag upright and squeeze out meringue, creating either an elongated cylinder or a "kiss" shape with a fairly pointy tip, about an inch tall.
  • Place the sheeets in the oven and bake for approximately 1 to 2 hours, until firm but not brown. You'll want to rotate the sheets at the first [and third] half hour and swap them at the 1 hour point.  
  • Let the caps and tips stand for a few moments on the cookie sheets.
  • Then, remove the mushrooms on their parchment to wire racks to cool completely.
  • When the mushrooms are cool, you may store them in pieces in a spacious air-tight container or assemble right away.
  • To assemble, melt the chocolate in a heat-proof bowl over boiling water or in slow bursts at half-power in the microwave.
  • OPTION A: Carefully make a small indentation in the centre underside of each mushroom cap with the back of a spoon or the tip of a knife. Working one at a time, fill the hollow in a cap with about a 1/4 teaspoon of melted chocolate. Then, press the top of a stem into the indentation. If possible, cool cap-side down on a tray until the seal is firm. 
  • OPTION B: Coat the undersides of the caps with a bit of chocolate. With snips or a sharp knife, cut off any of the pointy "tips" of the stems you might have made. Use additional chocolate to attach the stems to the caps. Cool completely until the seal is firm.
  • Store in a dry, air-tight container until ready to use.
  • If desired, dust with lemon zest and icing sugar when you assemble the cake.

Notes

*Note: If you're having trouble getting your egg-whites to peak, try incorporating 1/4 tsp Cream of Tartar.
This recipe is an amended form of a version I published on my former website, The Lunchbox Season.