How to Make It
Preheat oven to 450°.
Line a rimmed baking sheet with foil; place a wire rack on pan. Coat rack with cooking spray. Place 1 chicken, breast side down, on a cutting board. Using kitchen shears, cut along either side of backbone; discard bone. Turn chicken over; press down on the thighs and wings with the heel of your hand. Arrange chicken, breast side up, on rack. Repeat procedure with remaining chicken.
Starting at the neck of 1 chicken, loosen skin from breasts and drumsticks by inserting fingers, gently pushing between skin and meat. Combine oil, sage, rind, 1/2 teaspoon pepper, 1/2 teaspoon salt, and garlic in a bowl. Rub sage mixture under loosened skin, over flesh. (Do not season other chicken.) Add 3/4 cup water to pan. Bake chickens at 450° for 40 minutes or until a thermometer inserted into thickest part of thigh registers 165°. Let stand 10 minutes. Remove skin from both chickens; discard skin. Sprinkle the unseasoned chicken with 1/2 teaspoon pepper and remaining 1/2 teaspoon salt. Carve both chickens. When cool, shred the unseasoned chicken, keeping light and dark meat separate. Reserve shredded chicken for Thai Green Curry Chicken and Chicken Tinga Tacos.
Combine remaining 1/4 teaspoon pepper, remaining 2 tablespoons hot water, mayonnaise, juice, and anchovy paste in a large bowl. Add radicchio and kale; toss. Sprinkle with Parmesan. Serve with garlic-sage chicken.