In the bowl of a food processor, process the garlic, 1/4 cup edamame, cilantro and salt until it becomes a paste. With the food processor running, add 1/4 cup olive oil. Season to taste with lemon juice, salt and pepper. Set the pesto aside.
Season the halibut on both sides with salt and pepper. Heat 1 tablespoon olive oil in a non-stick oven-safe pan over medium high heat. Sear the halibut on one side for about 3 minutes. Gently turn the fillets and place in the oven to roast for about 4-6 minutes, depending on the thickness of the fish. The halibut should just be flaking but not dry.
Heat remaining tablespoon of olive oil in a small pan over medium heat. Add remaining edamame to the pan, along with the spinach. Pour the chicken stock in and let it come to a bubble. Season with salt and pepper and stir in the butter and 1-2 tablespoons of the pesto.
To serve, divide the edamame and spinach between 4 plates. Top with the halibut, and put a dollop of pesto on top of the fish. Garnish with cilantro, if you wish. Serve immediately.