Käsespätzle (German Cheese Spaetzle)

Steps

1. In a large bowl, mix the flour, the fine salt (keep a pinch back for the onions) and grated nutmeg. Make a well, crack in the eggs and pour in the whole milk. Beat with a wooden spoon for 5 minutes, lifting the batter as you go: it turns smooth and elastic, and bubbles form and pop on the surface. It should fall from the spoon in a thick, slow ribbon; if it's too stiff to spread, loosen it with 1 tablespoon of water. Let it rest for 15 minutes while you start the onions.
2. Peel the yellow onions and slice them into thin 1/8 inch (3 mm) half-moons. In a large skillet over medium heat, melt 40 g (3 tablespoons) of the butter with the neutral oil, then add the onions and the pinch of salt you kept back. Cook for 20 to 25 minutes, stirring often: they soften, turn blond, then brown. For the last 3 minutes, raise the heat and stir constantly until the edges are mahogany brown and crisp. Spread them on paper towels: they keep crisping as they cool.
3. While the onions cook, preheat the oven to 400°F (200°C) and butter a 10 x 8 inch (25 x 20 cm) baking dish with the remaining 10 g (2 teaspoons) of butter. Bring 4 l (about 4 quarts) of water to a boil in a large pot, add the coarse salt, then adjust the heat to keep a steady simmer. Mix the shredded Emmental and the grated hard cheese in a bowl.
4. Wet a spaetzle board, or a small cutting board, and the blade of a large knife. Spread about 3 tablespoons of batter thinly along the edge of the board, hold it over the water and quickly scrape thin strands of batter into the pot, dipping the blade in the water between strokes. With a spaetzle press or slider, simply push the batter through the holes.
5. Work in small batches: the spaetzle float to the surface in 1 to 2 minutes. Leave them for 30 seconds more, then lift them out with a slotted spoon, give them one shake and drop them straight into the baking dish.
6. As soon as a layer of spaetzle covers the bottom of the dish, scatter a handful of the cheese mixture and a grind of black pepper over it. Keep alternating spaetzle and cheese, about 4 layers, and finish with cheese. Drizzle 4 tablespoons of the cooking water over the top: it helps the cheese melt into a sauce instead of clumping.
7. Bake for 10 minutes at 400°F (200°C), until the cheese is melted, stretchy and bubbling at the edges.
8. Take the dish out, pile the fried onions and snipped chives generously on top, and serve right away, pulling up strings of cheese with the spoon.