Preheat oven to 350 degrees F (175 degrees C). Grease a 9x13-inch baking pan with cooking spray.

Whisk buttermilk and egg together in a shallow bowl.

Combine flour, ground pecans, sesame seeds, paprika, salt, and black pepper in a deep dish.

Dip each chicken breast in the buttermilk mixture and transfer to the flour mixture; turn to coat.

Arrange coated chicken in the baking pan. Drizzle melted butter on top. Sprinkle pecan halves over chicken.

Bake in the preheated oven until coating is golden, about 30 minutes. Scatter red grapes and green grapes into the baking pan. Continue baking until an instant-read thermometer inserted into the center of the chicken reads 165 degrees F (74 degrees C), about 30 minutes more.