Step 1

Preheat the oven to 375 ̊. Spread the walnuts on a baking sheet and toast in the oven, tossing once, until fragrant, 5 to 7 minutes.

Step 2

Divide the Brussels sprouts between 2 baking sheets and toss with the olive oil. Sprinkle with the salt and pepper and roast, tossing halfway through, until golden brown and tender, 25 to 30 minutes.

Step 3

Meanwhile, combine the balsamic vinegar and sugar in a saucepan. Bring to a boil, then reduce the heat to medium low and simmer until very thick, 15 to 20 minutes. Drizzle the balsamic reduction over the roasted Brussels sprouts. Sprinkle with the walnuts before serving.