Preheat a waffle maker to medium and set the oven to 140°C.
Melt the butter in a saucepan over low heat and allow it to cool.
Whisk the flour, half the milk, 3 eggs, baking powder, salt, and most of the butter into a smooth batter.
Stir 3 tablespoons of chives into the batter.
Grease the waffle maker with the remaining butter and cook batter until golden-brown.
Place cooked waffles on a baking tray in the oven to keep warm.
Bring a pan of water with vinegar to a simmer and create a vortex.
Poach duck eggs for 3 minutes before chilling them in iced water.
Wilt the spinach in a hot pan with butter and season with salt and pepper.
Reheat the poached eggs in boiling water for 1 minute.
Mix the crème fraîche with the remaining chives and seasoning.
Serve waffles topped with spinach, smoked salmon, a poached egg, and crème fraîche.