Serve this dip warm or at room temperature with Spiced Flatbread.
If using canned pumpkin, begin recipe with step 2. If using squash, heat oven to 375 degrees. Cut squash in half and remove seeds. Place halves cut side down on a parchment-lined baking sheet and roast until very soft, about 1 hour. Let cool slightly and scrape the flesh into a bowl. Set aside.
Meanwhile, place a small skillet over medium-high heat. Add cumin, mustard, and coriander seeds and toast, shaking pan, until seeds become fragrant, about 1 minute. Remove from heat and let cool. Grind finely in a spice grinder.
Combine squash or pumpkin, the mixed ground spices, olive oil, chickpeas, salt, pepper, lemon juice, and thyme leaves in a food processor. Process until smooth, about 30 seconds. Transfer to a serving dish and garnish with thyme sprigs, if desired. Serve immediately or keep refrigerated, covered, for up to 4 days.
3-pound butternut squash can be replaced with 15-ounce can pumpkin puree