1. Make the Croutons
Preheat the oven to 350°F (175°C).
Spread the bread cubes out onto a baking sheet. Drizzle with 1 tablespoon of olive oil and gently squeeze to help the bread absorb the oil. Bake for 30–40 minutes, until dried out and crisp. Transfer to a large bowl and set aside.

2. Cook the Aromatics and Mushrooms
In a large, wide-bottomed pan, heat 2 tablespoons olive oil and 2 tablespoons vegan butter over medium heat. Add the garlic and cook for 1 minute.
Add the leeks and sauté for 5–10 minutes until soft and fragrant. Season with salt and pepper.
Add the mushrooms and thyme sprigs. Cook for 10–15 minutes, until the mushrooms release their juices and the liquid has mostly evaporated. Season again with salt and pepper.

3. Deglaze and Combine
Pour in the white wine and cook for 5 minutes, until the wine is nearly all reduced. Stir in the chopped sage, then remove from heat. Discard thyme sprigs.
Spoon the mushroom mixture over the bread cubes. Pour in the vegetable stock and stir gently to combine—the mixture should be moist and soft.

4. Assemble and Bake
Grease an 8 x 10-inch baking dish with vegan butter. Transfer the stuffing mixture into the dish and spread evenly. Drizzle the top with 2 tablespoons of melted vegan butter.
Bake for 40 minutes, or until golden and slightly crisp on top.