Toast the almonds in a 190C/375F oven until lightly browned, about 10 minutes. Cool.
Heat the olive oil in a skillet and saute the onion and garlic for 3 minutes. Add the mushrooms, thyme, salt, and black pepper and cook until the mushrooms are browned and any liquid has evaporated.
Use a food processor to grind the almonds into a paste. Add the mushroom mixture and continue to process until smooth. Chill before serving.