Darkest Chocolate Crêpe Cake

For the crêpes:
6oz cold unsalted butter, cut into pieces, plus melted for pan
8oz semisweet chocolate, finely chopped
1 ½ cups flour
1/3 cup sugar
½ teaspoon salt
2 ½ cups full-cream milk, at room temperature
6 large eggs, at room temperature
1 tablespoon pure vanilla extract

1. Bring ¼ cup water to a rolling boil in a small saucepan over medium-high heat. Add butter, 1 piece at a time, whisking to combine after each addition. Remove from heat; stir in chocolate until completely melted. Set aside.
2. Whisk together flour, sugar and salt in a medium bowl. Whisk together milk, eggs and vanilla in another medium bowl. Gradually add milk mixture to flour mixture, whisking until smooth. Add chocolate-butter mixture, whisking until smooth. Pour through a fine sieve into an airtight container; discard lumps. Refrigerate at least 2 hours or up to overnight.
3. Lightly coat an 8-inch crêpe pan or non-stick skillet with melted butter. Heat pan over medium heat until just starting to smoke. Remove pan from heat; pour 2 tablespoons batter into pan, swirling to cover bottom. Reduce heat to medium-low; return pan to heat. Cook, flipping once, until edges are golden and centre is dry, about 30 seconds per side.
4. Slide crêpe onto plate. Repeat process with rest of batter. Crêpes can be refrigerated, covered, up to 1 day.

To construct cake:
Place a crêpe on a flat serving plate. Spread with 3 tablespoons of filling. Top with another crêpe. Continue layering with filling, using about 32 crêpe s and ending with a crêpe on top. Refrigerate until firm, about 15 minutes.
Spoon ½ cup of chocolate glaze on top of cake, spreading to edges. Spread remaining glaze around sides of cake, coating completely. Refrigerate until glaze is firm and set, about 20 minutes. Cake can be refrigerated up to 3 days. Garnish with toasted and candied hazelnuts.

Chocolate Glaze: (makes 2 cups)
1 ¼ cups heavy cream
1 tablespoon light corn syrup
Pinch of salt
10oz semisweet chocolate, finely chopped

Bring cream, corn syrup and salt to a boil in a medium, heavy saucepan over med-high heat. Remove from heat. Add chocolate; swirl pan to cover completely with cream. Let stand about 5 minutes. Stir until smooth. Let cool completely.

Hazelnut Filling: (makes 8 cups)
2/3 cup heavy cream
6 large egg whites
1 2/3 cups sugar
14 oz unsalted butter, cut into pieces, softened
1 teaspoon pure vanilla extract
1/3 cup hazelnut cream*
pinch of salt

1. Put cream into the bowl of an electric mixer fitted with the whisk attachment; beat on medium-high speed until soft peaks form, about 4 minutes. Transfer to a medium bowl. Refrigerate 1 hour.
2. Whisk egg whites and sugar in the clean mixer bowl over a pan of simmering water until sugar has dissolved and mixture registers 160˚F, 2 to 3 minutes.
3. Attach bowl to mixer fitted with clean whisk attachment; beat on high speed until slightly cooled and stiff (but not dry) peaks form, about 5 minutes.
4. Fit mixer with paddle attachment. With mixer on med-low speed, add butter, several pieces at a time, mixing well after each addition (meringue will deflate slightly as butter is added). Add vanilla, hazelnut cream*, and salt; mix until mixture comes together, 3 to 5 minutes. Fold in refrigerated whipped cream with a rubber spatula. Use immediately.


Candied Hazelnuts
9 hazelnuts, toasted and peeled
1 cup sugar

1. Thread each hazelnut onto a tip of a long wooden skewer; set aside. Place a cutting board along the edge of a countertop; set a baking sheet on the floor next to edge.
2. Cook sugar and ¼ cup water in a medium, heavy saucepan over medium heat, stirring occasionally, until sugar has dissolved. Continue to cook, without stirring, until syrup comes to a boil, washing down sides with a wet brush to prevent crystals from forming. Let boil until syrup turns light amber, about 5 minutes; remove from heat. Let stand until slightly cooled, 8 to 10 minutes.
3. Dip 1 skewered hazelnut into syrup, coating completely and letting excess syrup drip back into pan. When dripping syrup becomes a thin string, secure end of skewer under cutting board, letting caramel string drip over edge onto baking sheet. Repeat with remaining hazelnuts. Let stand until caramel has hardened, about 5 minutes. Break strings to about 4 inches. Carefully remove skewers.