Preheat oven to 400F/200C, line a baking tray with parchment paper. Chop the pumpkin into 1.5-inch pieces, add to a large mixing bowl. (If using butternut squash, peel the skin). In a small bowl add the oil, 1 clove garlic, pumpkin pie spice, cardamom, and salt. Whisk to combine. Drizzle the mixture over the pumpkin and toss to combine.
Transfer the pumpkin to the baking tray, spreading out in an even layer. Bake until fork tender and golden at the edges, 25-30 minute. (Remove and toss the pumpkin with spatula halfway through to ensure all sides are evenly roasted).
Toast the hazelnuts in a small skillet on medium-high heat, stirring often, until lightly browned and aromatic, 7-10 minutes.
In a large bowl add the garlic, apple cider vinegar, maple syrup, chili flakes, and salt. Add the cooked pumpkin and sprinkle with the parsley, gently toss to combine.
Slather a plate with a thick layer of hummus and gently pour the roasted pumpkin on top. Sprinkle with toasted hazelnuts and serve.