In a large skillet set over medium-low heat, melt the butter until it begins to gently bubble.
Stir in the salt, black pepper, brown sugar, and vegetable broth. Allow the mixture to come to a soft simmer, infusing the liquid with rich, buttery flavor.
Reduce the heat to low, then add the chopped carrots, broccoli, and cauliflower. Toss everything thoroughly so the vegetables are evenly coated in the buttery broth.
Cover the skillet partially and let the vegetables cook for about 7 minutes, stirring occasionally, until they reach a tender-crisp consistency. If you prefer your vegetables more tender, continue cooking for up to 10 minutes, adding a splash of broth as needed to maintain moisture.
Transfer to a serving dish and garnish with a scattering of freshly chopped herbs, if desired. Serve warm.