Old-Fashioned Berry Layer Cake

Directions

1. 1
   Preheat the oven to 350F.
2. 2
   Butter two 9-by-2-inch round cake pans; set aside.
3. 3
   Into a large bowl, sift together flour and cornstarch; set aside.
4. 4
   In the bowl of an electric mixer fitted with the whisk attachment, combine the whole eggs, egg yolks, granulated sugar, salt, and 1 teaspoon vanilla extract.
5. 5
   Beat on high speed until thick and pale (it should hold a ribbon-like trail on the surface when the whisk is raised), about 5 minutes; scrape down the sides of the bowl as needed.
6. 6
   Add flour mixture to egg mixture.
7. 7
   With mixer on low speed, beat until just combined.
8. 8
   Add oil in a steady stream, mixing until just combined.
9. 9
   Remove bowl from mixer.
10. 10
    Using the whisk, fold mixture several times.
11. 11
    Divide batter between pans, and smooth with an offset spatula.
12. 12
    Bake, rotating pans halfway through, until the cakes are springy to the touch and a cake tester inserted in the centers comes out clean, about 30 minutes.
13. 13
    Immediately invert cakes onto a wire rack.
14. 14
    Then reinvert cakes, and let them cool completely, top sides up.
15. 15
    In the bowl of an electric mixer fitted with the whisk attachment, combine cream, confectioners sugar, and remaining teaspoon vanilla extract.
16. 16
    Scrape in vanilla seeds, if using.
17. 17
    Starting on low speed and gradually increasing to medium-high, whip until stiff peaks form, about 2 minutes.
18. 18
    Using a serrated knife, trim the tops of the cakes to make level.
19. 19
    Slice each cake in half horizontally into two layers.
20. 20
    Place one of the bottom layers on a serving plate.
21. 21
    Spread a quarter of the whipped cream over the layer; arrange a quarter of the mixed berries on top.
22. 22
    Repeat with remaining cake layers, cream, and berries; garnish top with mint leaves, if using.
23. 23
    Serve immediately; slice with a serrated knife.