In a bowl, soak the livers in the milk for 2 hours. Drain well.
In a large saute pan or skillet, melt 4 tablespoons of the butter over medium-high heat. Add the onions and cook, stirring, until soft, about 3 minutes. Add the garlic and cook until fragrant, about 30 seconds. Add the chicken livers, thyme, salt, and pepper and cook, stirring, until the livers are browned on the outside and still slightly pink on the inside, about 5 minutes. Add the Marsala and cook until most of the liquid is evaporated and the livers are cooked through but still tender.
Remove from the heat and let cool slightly
In a food processor, puree the liver mixture. Add the remaining butter in pieces and pulse to blend.
Line ramekin with plastic wrap Pack the pate into a ramekin. Cover with plastic and refrigerate until firm, at least 6 hours.
To serve, unmold the ramekin place on a plate garnished with greens. Garnish the top with thyme. Serve with crackers.