Preheat the oven to 325oF. Place the hazelnuts in a single layer on a baking sheet, and bake for about 10 minutes, shaking the pan occasionally, until the hazelnuts are golden and fragrant.
Remove the hazelnuts from the oven and allow them to cool at room temperature. Once they hazelnuts are cool rub them with your hands, or between two clean kitchen towels, to remove the skin.
Reserve ¼ cup of hazelnuts and cut in halves. Place the remaining hazelnuts into the food processor. Process at high speed, and then add garlic, manchego, arugula, hazelnut oil and balsamic vinegar, and process until smooth. (If the pesto is too tick, add a little bit of water to thin it.)
Keep the oven at 400oF. Drizzle the pumpkin wedges with olive oil and season with salt and pepper. Place the wedges on a rimmed baking sheet and roast for about 20-30min until soft and slightly browned on the edges. Remove the pumpkin from the oven. When the pumpkin is cool enough, remove the skin and cut the pumpkin into one-inch cubes.
Arrange the beets and pumpkin on individual plates, adjust the seasoning, drizzle with balsamic vinegar and hazelnut oil, top with pesto and remaining hazelnuts, and serve immediately.
Aleksandra aka QueenSashy is a scientist by day, and cook, photographer and doodler by night. When she is not writing code and formulas, she blogs about food, life and everything in between on her blog, Three Little Halves. Three Little Halves was nominated for 2015 James Beard Awards and the finalist for 2014 Saveur Best Food Blog Awards. Aleksandra lives in New York City with her other two halves, Miss Pain and Dr. V.