Preheat the oven to 400F.
Add the lentils to a medium saucepan and cover with at least four inches of water. Cover, bring to a boil, then reduce to low and simmer for 15-25 minutes, or until the lentils are just tender but not mushy. Cooking times vary depending on the type and freshness of lentils used, so start testing at 15 minutes. Drain and set aside.
Meanwhile, add the butternut squash to a rimmed baking sheet, drizzle with 1 tablespoon olive oil, and sprinkle with ¼ teaspoon salt.
Place in the oven and roast for 20-25 minutes, flipping halfway through, or until the squash is golden brown on each side and cooked through.
Make the dressing by whisking the vinegar, garlic, maple syrup, mustard, and salt in a medium bowl. Drizzle in the olive oil and whisk until the dressing is smooth and well combined.
Combine the warm, drained lentils with the dressing in a large bowl, tossing to combine. Let sit for 5 minutes for the dressing to absorb.
Add the roasted squash, microgreens, and pumpkin seeds tossing to combine. Serve immediately, or store, tightly sealed in the fridge for up to 5 days.