Preheat oven to 400°F. Line two large rimmed baking sheets with parchment paper. Toss butternut squash cubes with 2 tablespoons olive oil, salt, and pepper. Spread in single layer on one baking sheet.
Roast squash for 15 minutes. Meanwhile, toss Brussels sprouts with remaining olive oil and season. Add to second baking sheet. Continue roasting both for 15-20 minutes until tender and caramelized.
Bring large pot of salted water to boil. Cook tortellini according to package directions (3-5 minutes for fresh). Drain and set aside.
Season chicken strips generously with smoked paprika, dried thyme, salt, and pepper. Heat remaining olive oil in large cast iron skillet over medium-high heat.
Add chicken in single layer and cook 4 minutes without moving to develop sear. Flip and cook another 4-5 minutes until cooked through. Remove to plate.
In same skillet, melt butter over medium heat. Add minced garlic and cook 1 minute until fragrant. Add drained tortellini and toss to coat in garlic butter.
Return chicken to skillet. Add roasted butternut squash and Brussels sprouts. Gently toss everything together. Season with additional salt and pepper if needed.
Garnish with fresh thyme and serve immediately while hot.