Preheat oven to 425?F and set a baking sheet to the side.

Trim the ends of the Brussels sprouts and then cut in half. Remove any flimsy leaves if necessary.

Toss Brussels sprouts in a large bowl with olive oil, 1 tsp. salt, and black pepper until lightly and evenly coated.

Arrange Brussels sprouts, cut side down, on a baking sheet. Roast in the oven for ~20 minutes until tender and deeply golden, without flipping them while roasting.

Meanwhile, make the honey balsamic sauce. Heat honey in a saucepan over medium-high heat until it begins to bubble, about 1-2 minutes.

Remove from heat and add balsamic, Dijon, garlic, chili flakes, and the remaining 1/2 tsp. salt.

Return to medium-low heat, add the butter, and cook until the sauce thickens, about 5 additional minutes.

Spoon glaze over roasted Brussels and toss to coat or serve sauce on the side. Garnish with lemon zest and green onions, if desired.