Set Your Oven: Begin by setting your oven to 400°F (200°C) and allow it to fully heat while you prepare the ingredients.
Roast the Butternut Squash :Toss the cubed butternut squash with olive oil, salt, and pepper. Spread the squash evenly on one of the prepared baking sheets. Roast for 25-30 minutes, flipping halfway, until golden and tender.
Roast the Brussels Sprouts: Toss the halved Brussels sprouts with olive oil, salt, and pepper. Spread them on the second baking sheet in a single layer. Roast alongside the butternut squash for about 20-25 minutes, until crispy on the outside and tender inside.
Prepare the Steak: Pat the flank steak dry with paper towels. Season both sides with smoked paprika, chili powder, salt, and freshly ground black pepper. Warm 2 tablespoons of olive oil in a large pan on medium-high heat until it shimmers, signaling it's ready for cooking.
Cook the Steak: Sear the steak for about 3-4 minutes on each side until a nice crust forms. Lower the heat to medium, add the butter, minced garlic, and thyme to the skillet. Tilt the pan slightly and spoon the melted garlic butter over the steak as it cooks for an additional 2-3 minutes, or until your desired level of doneness. Remove the steak from the skillet and let it rest for 5 minutes before slicing against the grain.
Serve: Slice the steak thinly and serve alongside the roasted butternut squash and Brussels sprouts. Pour the leftover garlic butter from the pan over the steak to enhance its flavor with a rich, buttery finish.