Preheat the oven to 425 degrees.
To roast the beets: Place the beets, 1 tablespoon olive oil, 1/4 teaspoon salt and 1/8 teaspoon pepper in a roasting pan and cook until the beets are tender, about 40 minutes. When they are cool enough to handle, remove the skins and slice the beets.
Place the beets in a medium-sized mixing bowl and toss with the remaining 1 tablespoon olive oil, 1/4 teaspoon salt, and 1/8 teaspoon pepper.
To make the Walnut Gorgonzola Dressing: Place a large skillet over medium-high heat and, when it is hot, add the extra-virgin olive oil. Add the walnuts and cook until they are browned, about 2 to 3 minutes. Transfer to a small mixing bowl and when the walnuts have cooled to room temperature, add the onion, basil, vinegar and salt.
Place the Gorgonzola cheese and cream in a blender or food processor fitted with a steel blade and process until smooth. Transfer to the bowl with the walnuts and mix to combine.
Divide the arugula between 4 to 6 plates and top with equal amounts of beets. Serve immediately with a large dollop of Walnut Gorgonzola Dressing.