Preheat oven to 425°F.
Combine Maple Miso Sauce in a small mixing bowl and whisk all together.
Fold two 15-inch square pieces of parchment paper in half. Starting from the folded edge, cut out half of a heart shape. When you unfold the paper, it should be the shape of a heart.
Unfold and place vegetables on one side of each sheet next to the crease. Season with salt and pepper.
Drizzle 1 - 1 ½ tbsp. of Maple Miso Sauce over the vegetables and lay a sprig of thyme.
Fold other half of parchment over to cover the vegetables.
Starting at the top of the half heart shape, make small, tight, overlapping folds along the open edge to seal and make a packet. More folds will make a tighter seal to keep steam in.
Place packets on a large rimmed baking sheet (or cast iron skillet) and bake 15 minutes in the preheated oven. It’s ready when the packets look puffed-up and slightly browned.
Remove packets from oven and transfer to individual serving plates (or serve in the cast iron skillet).
Slit tops with kitchen shears, gently open and serve. Watch out for hot steam escaping from the pouch.