Chocolate Gateau

Gather all ingredients and measure flour and cocoa by fluffing, sprinkling into cups and levelling. Position a rack in the center and preheat oven to 175°C (350°F); for convection reduce to 160°C.

Use an 8-inch (20-cm) light-colored round cake pan. Trace the pan bottom on parchment paper, then fold the remaining rectangular sheet (about 20 × 32 cm) in half lengthwise and crease the center.

Cut just inside the traced circle and set aside. Separate the rectangular sheet if still attached.

With the rectangle folded lengthwise, fold up the long edges by 1.3 cm and crease. Cut notches every 1.3 cm, stopping at the crease.

Unfold and cut along the center crease to make two notched strips. Line the pan sides, flaps flat against the bottom, overlapping the ends.

Place the parchment circle over the flaps to cover the bottom. No greasing needed.

Combine ¼ cup cake flour, ¾ cup Dutch-process cocoa powder and ⅛ tsp Diamond Crystal kosher salt. Sift through a fine-mesh sieve.

Press any cocoa lumps through the sieve with a spoon. Repeat sifting 2–3 times, then set aside.

Wipe the mixer bowl clean and dry. Separate 5 large eggs (50 g each without shell), whites into the mixer bowl and yolks into a separate large bowl.

Set a heatproof bowl over a saucepan of barely simmering water. Cut 9 Tbsp unsalted butter into small cubes.

Break up the egg yolks with a whisk, then add ½ cup sugar (for the yolks).

Whisk until thick and pale. Set aside.

Add 9 Tbsp unsalted butter and ¾ cup chocolate chips to the double boiler. Stir occasionally until melted and smooth and 50°C (122°F) on a thermometer; keep water and steam away from the chocolate.

Once the chocolate mixture reaches 50°C (122°F), remove the bowl from the double boiler. Wipe its bottom dry.

Add one-quarter of the warm chocolate mixture to the yolks. Whisk until smooth.

Add the chocolate mixture in three more additions, whisking well after each. Keep the mixture warm.

Microwave 2 Tbsp milk in 10-second intervals until steaming. Add to the batter and whisk until smooth.

Using the whisk attachment, beat the room-temperature egg whites on medium speed until foamy.

Gradually add ½ cup sugar (for the whites) in three additions while beating.

Increase to medium-high speed and beat until very soft peaks form.

Lift the whisk: the whites should fall softly a few times, then stop, not run off continuously. Do not overbeat.

Add one-third of the whipped egg whites to the chocolate batter. Stir gently with a whisk in a scooping motion until marbled.

Add all the sifted dry ingredients (flour, cocoa and salt mixture).

Continue mixing with a scooping motion until most of the dry ingredients are incorporated. A few dry spots should remain.

Add the remaining egg whites. Switch to a silicone spatula and gently fold from the bottom.

Fold just until the batter is uniform, with no white streaks or dry spots. Avoid overmixing.

Pour the batter into the prepared pan in one spot. Drop the pan twice on the countertop to release air bubbles.

Bake at 175°C (350°F) for 55–60 minutes, until a toothpick near the center comes out with moist crumbs but no wet batter.

Remove from the oven and firmly drop the pan once on the countertop. Cool completely in the pan on a wire rack, then wrap tightly and refrigerate overnight.

Remove the cake from the refrigerator about 15 minutes before serving. Run a knife around the edges and carefully invert the cake onto your hand.

Flip the cake right side up onto a serving plate. Remove the side parchment, leaving the bottom parchment in place.

Whip ⅔ cup cold heavy (whipping) cream with 4 tsp sugar until medium peaks form.

Check the peaks hold their shape but curl at the tips. Lightly dust the cake with confectioners' sugar and place the whipped cream in the center.

Spread the cream into a circle, leaving a 2.5-cm (1-inch) border around the edge.

Halve ½ lb hulled strawberries lengthwise. Arrange a first ring cut side up, tips outward, near the cream edge, then a second ring cut side down, slightly overlapping.

Arrange the remaining strawberries in the center. Garnish with fresh mint leaves and lightly dust with confectioners' sugar.

Dust the cake with confectioners' sugar and decorate with 10 raspberries.

Store leftover cake in an airtight container in the refrigerator for 3–4 days, or freeze for up to 2 weeks.