Preparation

Bake the cakes

• Place a rack in the middle position in your oven and preheat to 350°F. Generously butter the bottoms and sides of two 9-inch round cake pans with 2-inch-high sides (preferably nonstick). Line the bottoms only with parchment paper. Sift together the flour, baking powder, and salt, then place it back into the sifter.
• In a large bowl with an electric mixer on high, beat the yolks for 3 minutes. With the mixer running, slowly add half the sugar; continue beating until thick, light yellow ribbons form, about 5 minutes more. Beat in the extracts. Sift the flour mixture over the batter and stir in with a wooden spoon, just until no white flecks appear (don’t overmix!). Blend in the butter. Wash the beaters well and dry.
• In another large bowl, beat the egg whites and cream of tartar with the mixer on high until frothy. Gradually add the rest of the sugar and continue beating until stiff peaks form (the whites will stand up and look glossy but not dry). Fold about one-third of the whites into the batter, then the remaining whites. Don’t worry if you still see a few white specks, as they’ll disappear during baking.
• Divide the batter evenly between the 2 prepared cake pans and bake on the middle oven rack until the tops look set and golden (not wet or sticky) and a pick inserted in the centers comes out with moist crumbs clinging to it, about 25 minutes. Touch the cakes gently in the center. When they spring back, they are done. Watch carefully and don’t let the tops brown. Transfer to wire racks and let cool in the pans for 15 minutes. Remove the cakes from the pans and let cool completely on the racks. Peel off the parchment liners.

Assemble, frost, and decorate the cakes

• 和船体的草莓洗净,然后干在纸上towels. Pick out 12 of the prettiest ones and set aside for decorating the top. Slice the remaining strawberries across into circles to use between the layers (you need about 4 cups). Rinse the raspberries and dry on paper towels. Pick out 12 of the prettiest ones and set aside. Rinse the blueberries and dry on paper towels. Pick out 25 of the prettiest ones and set aside. Cover the berries with a wet paper towel. Prepare the whipped cream, cover with a damp paper towel, and chill.
• 当蛋糕cooled completely, with a serrated knife cut each layer horizontally (with a sawing motion) into 2 equal layers—for a total of 4 thin layers. Brush away any crumbs. Place one layer, bottom side down, on a cake plate and spread with 1⁄2-inch-thick layer (about 1 cup) of the whipped cream. Scatter some sliced strawberries, raspberries, and blueberries over the top, pushing them down into the cream (this will help the layers stay together as you slice and serve this tall cake). Spread 1⁄3 cup cream over the top of the second layer and place, cream side down, on the first layer. Repeat in the same way with whipped cream and berries on top. Spread 1⁄3 cup cream over the top of the third layer and place, cream side down, on the second layer. Repeat with another 1⁄2-inch layer of cream and the remaining berries (excluding the reserved berries for the top). Spread 1⁄3 cup cream over the top of the fourth layer and place, cream side down, on the third layer. Fill in any empty spaces between the layers with whipped cream to even up the side. Brush away any crumbs. Refrigerate until chilled and set, 1 to 2 hours. Refrigerate the remaining whipped cream.
• Frost the side and the top of the cake with whipped cream, using a 1⁄2- to 3⁄4-inch layer of cream on the top. (Be sure to reserve some to pipe rosettes.) Use an icing spatula to smooth the side and top. Stand up a ring of whole strawberries about 11⁄2 inches from the edge, then arrange a circle of raspberries in the center. Fill up the space between the two rings of raspberries with blueberries. Fit a pastry bag with a large open-star tip (#172 or #2110/1M), fill it three-fourths full with the remaining whipped cream, and pipe a border of whipped cream rosettes on the top, around the outside rim of the cake.
• Refrigerate the cake for at least 1 hour or until serving time (but not more than 3 hours). Slice the cake with a sharp straight-edge slicing knife, not a serrated cake knife. This cake is best served the day it is made.

  TIP:Don’t freeze this cake. It will not look pretty or hold up when defrosted. The fruits will lose their shape, their colors will bleed, and the whipped cream frosting will lose its design.