In a medium pot, combine lentils, 4 cups of water, garlic, bay leaf, and ½ tsp. salt; bring to a boil over high heat. Reduce heat to medium-low and simmer for 20 to 30 minutes, until lentils are tender. Drain any excess water, and discard bay leaf.
Meanwhile, preheat oven to 425ºF.
Add Brussels sprouts, butternut squash, red onion, and thyme sprigs to a large rimmed baking sheet. Drizzle with olive oil, and season with coriander, paprika, remaining ½ tsp. salt, and black pepper; toss well to coat.
Roast for 40 minutes, tossing once midway through. Discard thyme sprigs (they should be mostly bare).
Prepare Maple-Mustard Dressing by combining vinegar, maple syrup and mustard in a glass jar or small mixing bowl; mix to combine. Gradually stream in olive oil, whisking constantly, until smooth. Season with salt and pepper.
Combine lentils and roasted veggies in a large serving bowl or platter. Add half of dressing and toss to combine. Drizzle remaining dressing overtop, and garnish with goat cheese and toasted pumpkin seeds.