Season the chicken thighs generously with salt and freshly ground black pepper and coat them in the flour, shaking off any excess. Heat a large heavy pot over medium heat. Add 1 tbs of the oil, 10g of the butter and half of the chicken. Cook, turning as needed, for 5 mins or until golden brown. Transfer the chicken to a plate. Repeat with the remaining chicken. Set aside.
Add the remaining oil and butter, onion and garlic and cook, stirring to scrape up any browned bits, for 3 mins or until the onion is tender and golden. Add the wine, bring to a boil and cook for 2 mins or until the wine has reduced slightly. Return the chicken to the pot. Add the chicken stock and bring to a simmer. Reduce the heat to low, cover and cook, stirring occasionally, for 30-35 mins or until chicken is tender and sauce has thickened.
Meanwhile, make the spaetzle. In a large bowl, whisk the flour, chives, parsley, 3 tsp salt and ½ tsp freshly ground black pepper. In a small bowl, whisk the eggs and stock until blended. Gradually whisk the egg mixture into the flour mixture. Meanwhile, bring a large pot of salted water to a boil over high heat, and then reduce the heat so the water is at a simmer.
Using a silicone spatula, press half the batter through the 5mm-wide holes of a spaetzle maker, or a colander, into the simmering water. Boil spaetzle for about 10 seconds or until tender. Using a slotted spoon, remove the spaetzle, drain and place on a baking tray. Repeat with remaining batter. Keep the cooked spaetzle warm until ready to serve.
Return the chicken braise to a simmer over medium heat. Add the sour cream and kale and stir to blend the sauce and wilt the kale. Divide the warm spaetzle among 4 shallow bowls. Spoon the chicken braise over the spaetzle and serve.