Preheat the oven to 400°F (200°C). Line a baking tray with parchment paper.

Roast the beets: Wrap each beet in foil and roast for 45–50 minutes until fork-tender. Let cool, then peel and pat dry.

Prepare the duxelles: In a skillet over medium heat, add olive oil, onions, and garlic. Sauté until soft. Add mushrooms, thyme, rosemary, salt, and pepper. Cook until moisture is gone. Stir in balsamic vinegar and cook 2 more minutes. Let cool completely.

Assemble the Wellington: Roll out the puff pastry. Spread Dijon mustard in the center. Layer mushroom duxelles, then place the beet(s) on top. Wrap tightly and seal the edges. Flip seam-side down. Decorate with cutouts if desired.

Bake: Brush with plant milk and bake for 25–30 minutes, or until golden brown. Let rest 10 minutes before slicing.

Serve: Slice and serve with balsamic glaze or vegan gravy and your favorite sides.