Pilgrim Whoopie Pie

Name: Pilgrim Whoopie Pie
Ingredients: 3/4 cup (1 1/2 sticks) unsalted butter, at room temperature; 1 1/2 cups granulated sugar; 1 3/4 cups cocoa powder; 3 large eggs, at room temperature; 2 1/3 cups all-purpose flour; 1 1/4 teaspoons baking soda; 1 1/2 teaspoons baking powder; 1 teaspoon kosher salt; 1/2 teaspoon instant espresso powder; 1 1/2 cups ice water; Nonstick cooking spray; 5 sheets gelatin; Ice water, for blooming the gelatin; 1 1/4 cups granulated sugar, plus 2 teaspoons; Generous 1/2 cup corn syrup; 6 large egg whites, at room temperature; Pinch of kosher salt; Splash of lemon juice; Splash of vanilla extract; 7 tablespoons unsalted butter, at room temperature; 1/2 cup granulated sugar; 3 large egg whites; 3/4 cup plus 1 tablespoon all-purpose flour; 1/2 teaspoon vanilla extract