Heat olive oil in a large skillet or Dutch oven over medium high heat. Sauté the onions for about 6 minutes, or until golden brown. Add the garlic, half the of dill and chives. Stir and sauté for another 2 minutes.
Add the spinach, salt, pepper, and cook for 4 minutes, just until it starts to wilt.
Add the basmati rice and chicken stock and stir. Bring it to a boil, cover and reduce the heat to low. Simmer for 22 minutes.
Stir in the butter, lemon juice, zest, remaining dill and chives and feta cheese. Serve immediately.