Heat a skillet over medium heat. Add the walnuts and cook until they start to become aromatic, about 5 minutes. Stir occasionally to prevent burning and toast evenly. Add the balsamic vinegar, stir to coat, and remove from the heat. Toss with sea salt and allow to cool.
Meanwhile create the dressing by whisking together the vinegar, oil, and sea salt.
Arrange the spinach in a large platter. Toss with the dressing. Top with the Raspberries, cheese, and caramelized walnuts. Enjoy!