Melt the butter and walnuts together in a skillet over medium-high heat. Toast, stirring, for a few minutes, then add the brown sugar and cinnamon and cook for another minute or so, stirring, until the sugar is melted and coats the walnuts evenly. Remove walnuts to a piece of parchment paper and spread immediately to separate into individual pieces.
Divide the mixed greens between two plates. Thinly slice the pear and layer over the greens. Finally, divide the Gorgonzola between the two plates, and finish with the cooled walnuts.
Whisk together the vinaigrette ingredients in a small bowl, then pour evenly over each salad. Serve immediately.