Preheat the oven to 350 degrees . In a medium bowl, combine the spinach, hummus, pine nuts and nutmeg. Season with salt and pepper.
Season the chicken with salt and place one-quarter of the hummus mixture on the right side of each breast. Fold the left side over the mixture. Using toothpicks, close the open sides.
Place the flour in a wide, shallow bowl and season with salt and pepper. Beat the eggs in another bowl and place the panko in a third bowl. Coat the stuffed chicken with the flour, shaking off any excess. Dip the chicken in the egg, then coat with the panko.
In a large skillet, heat the butter over medium-high heat until the foaming stops. Add the chicken and cook, turning once and adjusting the heat as necessary, until golden, 3 to 4 minutes per side. Transfer the chicken to a foil-lined baking sheet and bake for 10 minutes. Let rest for 5 minutes. Discard the toothpicks and slice each breast into pieces.