Butter or nonstick cooking spray, for the pans
2 cups (260 grams) cake flour
2 teaspoons baking powder
1/2 teaspoon fine salt
1/2 cup (120 milliliters) grapeseed oil
1 1/4 cups plus 2 tablespoons (275 grams) granulated sugar, divided
2 teaspoons vanilla extract
6 large egg yolks
1/2 cup (120 milliliers) whole milk
8 large egg whites
3/4 teaspoon cream of tartar
For the basil whipped cream:
2 1/2 cups (600 milliliters) heavy cream, plus more if needed, divided
1 to 1 1/2 cups (40 to 60 grams) lightly packed fresh basil leaves, chopped
2 tablespoons granulated sugar
1/2 teaspoon vanilla extract
For the assembly:
1 quart (580 grams) fresh strawberries
Make the chiffon cake: Arrange a rack in the middle of the oven and heat to 350°F (175°C). Grease and line the bottoms of 2 (8-inch or 20-centimeter) round cake pans with parchment paper and set aside.
Sift together the flour, baking powder, and salt and set aside.
In the bowl of a stand mixer fitted with the paddle attachment, beat together the oil and 1 1/4 cups (250 grams) of the sugar on medium speed for 1 minute. Add the vanilla and egg yolks, one at a time, and mix for about 3 minutes. The mixture will increase in volume and be pale in color. Stop the mixer and scrape down the bowl.
Turn the mixer to low and add the flour mixture in 3 batches, alternating with the milk, beginning and ending with the flour mixture. Mix on medium for no more than 30 seconds after the last streaks of the dry ingredients are combined. Pour the batter into a large bowl and set it aside.
Clean the mixer bowl thoroughly and dry it well. In the clean bowl of the stand mixer fitted with the whisk attachment, whisk the egg whites on medium-low speed until foamy. Add the remaining 2 tablespoons sugar and the cream of tar- tar and whisk on high until stiff peaks form.
Stop the mixer and carefully but deliberately fold the egg whites into the cake batter with a rubber spatula. Evenly divide the batter between the prepared pans.
Bake for 25 to 28 minutes, or until a toothpick inserted into the center of the cakes comes out clean. Let them rest on a wire rack until cool before running a paring knife or metal spatula around the edges of the cakes and removing them from their pans.
Make the basil whipped cream: Slowly heat 2 cups (480 milliliters) of the cream in a medium saucepan over medium-low heat until it begins to simmer. Meanwhile, gently muddle the basil leaves with a mortar and pestle.
Once the cream begins to steam and simmer, remove the pan f