Preheat oven to 400 degrees. Trim any rough ends off of brussel sprouts and slice in half. Whisk oil and syrup in a bowl; add sprouts and toss to coat. Spread in single layer on baking sheet, sprinkle with salt, and bake for 25-30 minutes, until easily poked with a fork and crispy on the edges.
Toss the walnuts with the roasted brussel sprouts, add freshly ground black pepper to taste and serve.
While the sprouts are roasting, heat a skillet over medium high heat. Once hot, add walnuts. Stir or toss continually so they don't burn. When you smell the toasty flavor or you see the nuts brown, remove from heat.