Vanilla Sponge Cake with Strawberry-Meringue Buttercream

Ingredients

• Cake
• Vegetable-oil cooking spray, for pan
• 2 1/4 cups cake flour (not self-rising)
• 1 1/2 cups granulated sugar
• 2 1/4 teaspoons baking powder
• 3/4 teaspoon kosher salt
• 1 stick unsalted butter, melted and cooled slightly
• 7 large eggs, separated, room temperature
• 2/3 cup whole milk, room temperature
• 1/2 teaspoon cream of tartar
• 2 teaspoons pure vanilla extract
• 3 pounds strawberries, hulled
• 1 3/4 cups granulated sugar
• 7 large egg whites
• 1/4 teaspoon kosher salt
• 4 sticks unsalted butter, room temperature, cut into pieces
• 1 teaspoon pure vanilla extract
• Confectioners' sugar, for dusting (optional)