How to Make It
Preheat the oven to 350°. Spread the hazelnuts on a pie plate and toast in the oven until fragrant, about 10 minutes. Wrap the nuts in a kitchen towel and rub them against each other to remove their skins. Let cool completely, then coarsely chop the nuts.
In a large nonstick skillet, heat 1 tablespoon of the butter. Fit the endives in the skillet, season with salt and pepper and cook over moderate heat, turning, until lightly browned and tender, about 12 minutes; remove to a plate. Add the spinach to the skillet, season with salt and pepper and cook, stirring, until just wilted, about 1 minute; remove to another plate.
Wipe out the skillet and add the remaining 1/2 tablespoon of butter. Add the scallops, season with salt and pepper and cook over moderately high heat until browned, about 1 1/2 minutes per side.
Add half of the Citrus Vinaigrette to the endives and half to the spinach; toss both gently. Arrange the spinach on 6 warmed plates and set 3 endive quarters on top of each serving with the endive bases touching. Place a scallop at the base of the endives and sprinkle the hazelnuts and herbs over all. Serve at once.