Toast the walnuts in a large dry skillet over medium heat. Keep a careful eye on them and shake the pan often as they can burn quickly. As soon as they start browning on the edges remove them from the heat. Remove the walnuts from the pan and set aside to cool.
Return the pan to the heat and add the olive oil. When hot add the onions and sauté until the onions soften and turn translucent about 4 minutes. Add in the garlic and sauete for a minute. Add the mushrooms, parsley, rosemary, thyme, salt, and sauté until the mushrooms have cooked and reduced in size, another 5 - 8 minutes. As the mushrooms cook they will release their own liquid. Add in the cherry port (or sherry) to deglaze the pan.
Add the mushrooms to the food processor (or let cool first) then place in food processor. Pulse, stopping to scrape the sides as needed until you reach the desired pâté texture.
Press into a container for serving using a spatula to smooth it, and let it chill completely in the fridge before serving.