Instructions

for the cake

Adjust oven rack to middle position and heat oven to 325 degrees. Lightly grease 9-inch springform pan, line bottom with parchment paper, and lightly grease parchment. Wipe any excess grease from sides of pan, leaving only a thin coat. Whisk 1 cup (4 ounces) bleached cake flour, ¼ cup (1¾ ounces) sugar, 1¼ teaspoons baking powder, and ¼ teaspoon table salt together in medium bowl. Whisk 3 large egg yolks, ¼ cup vegetable oil, ¼ cup water, and 1 teaspoon vanilla into flour mixture until smooth batter forms.
Using stand mixer fitted with whisk attachment, whip 3 large egg whites and ¼ teaspoon cream of tartar on medium-low speed until foamy, about 1 minute. Increase speed to medium-high and whip whites to soft, billowy mounds, about 1 minute. Gradually add remaining ¼ cup (1¾ ounces) sugar and whip until soft peaks form, about 2 minutes. Transfer one-third of whipped egg whites to batter; whisk gently until mixture is lightened. Using silicone spatula, gently fold remaining egg whites into batter.
Pour batter into prepared pan. Bake until top is golden brown and cake springs back when pressed lightly in center, 30 to 33 minutes.
Transfer to wire rack; let cool for 10 minutes. Run thin knife between cake and side of pan; remove side of pan. Invert cake onto wire rack, remove parchment, and then reinvert. Let cool completely, at least 1 hour.

for the strawberries and topping

Hull 2 pounds strawberries. Select 12 of most attractive mid-size strawberries. Place them broad side down on cutting board and trim left and right sides from each to create twelve 1-inch-thick slices. Transfer trim to small saucepan. Cut slices in half to create twenty-four ½-inch slices. (If any strawberries are more than ½ inch taller than others, trim bases and add trim to saucepan). Arrange slices, taller side down, on plate. Set sliced strawberries and saucepan aside.
Toss remaining hulled strawberries with ½ cup (3½ ounces) sugar, 2 tablespoons water, and pinch salt in bowl to combine. Microwave until sugar is mostly dissolved, 1 to 1½ minutes, stirring halfway through microwaving. Set aside for 1 hour, stirring once halfway through.

for the filling

Place ¼ cup heavy cream in small bowl. Sprinkle 1½ teaspoons unflavored gelatin over cream and let sit until hydrated, about 5 minutes. Microwave until mixture is smooth and fluid, 10 to 15 seconds (it’s  OK if some fat separates out). Stir in 2 teaspoons vanilla and pinch table salt. Whisk 2 cups plain whole-milk Greek yogurt in large bowl until smooth. Add gelatin mixture and, working quickly, whisk to incorporate.
Combine ⅔ cup (4⅔ ounces) sugar and remaining 1¾ cups cream in bowl of stand mixer fitted with whisk attachment. Whip on medium-low speed until whisk leaves trail, about 2 minutes. Increase speed to medium-high and whip until just stiff peaks form, 1 to 1½ minutes (do not overbeat). Whisk cream into yogurt mixture until combined. Fold briefly with silicone spatula, scraping bottom of bowl to ensure that all yogurt is evenly incorporated. Transfer to pastry bag fitted with ½-inch round tip and set aside. 
Place fine-mesh strainer over saucepan with strawberry trim. Transfer macerated strawberries to strainer, allowing syrup to drain into saucepan (do not wash bowl).
Split cake in half horizontally. Center clean springform ring, unclasped, on cake platter. Place bottom cake layer in ring and close clasp. Line inner surface of ring with 4-inch-tall strips of acetate. Arrange sliced strawberries, point side up and with taller side facing outward, around inside edge of ring, nestling them snugly (transfer any leftover slices to saucepan) (see “A” in “Assembling the Cake”). Line now-empty plate with paper towels. Transfer strawberries from strainer to prepared plate (do not wash strainer).
Starting at base of strawberry slices, pipe filling between slices (see “B” in “Assembling the Cake”). Pipe about 1 cup filling over center of cake and smooth with back of spoon (“C” in “Assembling the Cake”). Stand drained berries broad side down on cream, nestling them as snugly as possible (add any leftover berries to saucepan) (“D” in “Assembling the Cake”). Pipe cream in between strawberries to fill gaps (“E” in “Assembling the Cake”). Pipe cream over strawberries, leaving 1½ to 2 cups filling in bag. Smooth filling with back of spoon (cream needn’t completely cover berries) (“F” in “Assembling the Cake”). Place second cake layer on top and press gently (“G” in “Assembling the Cake”). Pipe ½-inch border around edge of cake. Pipe remaining cream over top and smooth, leaving outer edge at least ½ inch taller than rest of top (“H” in “Assembling the Cake”). Freeze until edge is firmly set, at least 2 hours or up to 4 hours.
Sprinkle 1 teaspoon unflavored gelatin over 1 tablespoon lemon juice and let sit until hydrated, about 5 minutes. Meanwhile, bring strawberry trim and syrup to simmer over medium heat and cook, stirring occasionally, until berries are very soft, 3 to 6 minutes. Place now-empty strainer over now-empty bowl and strain strawberry mixture, pressing on solids with spatula to release as much liquid as possible; discard solids. Transfer liquid 1-cup liquid measuring cup. If juices are less than ¾ cup, add hot water to make up difference; if greater than ¾ cup, pour off excess. Stir in gelatin until dissolved. Let cool until barely warm but still fluid, 20 to 25 minutes.
Unclasp springform ring and remove. Carefully peel away acetate (see “I” in “Assembling the Cake”). Transfer platter to refrigerator. With cake on refrigerator shelf, pour juice mixture over center top of gâteau, allowing it to fill hollow evenly (if juice mixture has thickened, warm gently until just fluid) (“J” in “Assembling the Cake”). Refrigerate for at least 4 hours or up to 24 hours. Let cake stand at room temperature for 45 minutes before serving.
Garnish with extra strawberries. To serve, dip sharp chef’s knife in very hot water and wipe dry between cuts. For each slice, saw gently to cut through whole berries. (Leftovers can be refrigerated for up to 2 days.)