Halve the delicata squash lengthwise and scrape out seeds and pulp using a spoon. Slice crosswise into 1/2-inch pieces.
Line a baking sheet with parchment paper. Layer the sliced delicata squash on baking sheet and drizzle with olive oil. Season liberally with salt and pepper. Roast for 40 minutes, tossing halfway for even roasting.
Assemble the Winter Salad:
Layer spinach, pomegranate seeds, feta and pepitas in a large serving bowl.
Toss salad with honey mustard vinaigrette immediately prior to serving or serve with dressing on the side.
Make the Honey Mustard Vinaigrette:
Mix vinegar, mustard, honey, salt, garlic powder and pepper in a sealable container. Shake vigorously to combine. Whisking constantly, stir in the olive oil in a steady stream. Use immediately or will keep in a sealed container in the fridge for 2 weeks.