Heat a pot over medium-low heat. Add the oat groats and toast for 2 to 3 minutes. Cover the oats with 2 cups of water. Bring to a boil, reduce to a simmer, and cook until the oats are tender; 45 to 55 minutes.
While the oats are cooking, peel and cut the butternut squash into ½” cubes and the fennel cored and chopped into ½” sized slices. Place on a roasting pan with olive oil and salt. Toss to coat. Roast until the squash is tender; 30 minutes or so.
When the oats and squash are done, place together in a bowl along with the pesto. Toss until everything is well combined. Grate parmesan on top before serving. Serve warm or save and place in the refrigerator to serve as a cold salad.
