Sweet Dough: * 5 cups all-purpose flour * 2 teaspoons baking powder * 1/2 teaspoon salt * 1/2 cup unsalted butter, softened * 1/4 cup vegetable shortening * 1 1/2 cups granulated sugar * 2 large eggs * 2/3 cup milk * 1 teaspoon vanilla extract Filling: * 1/2 cup granulated sugar * 2 tablespoons cornstarch * 1/8 teaspoon salt * 1/2 cup water * 1/4 cup milk * 2 large egg yolks * 2 teaspoon unsalted butter * 1/4 cup fresh lemon juice * 1 teaspoon lemon zest. grated