Preheat oven to 400°F. Wipe ¾ lb. Portobello mushrooms clean and remove the stems. Finely mince 1 clove garlic.
Lightly oil a baking sheet and place the mushrooms on top in a single layer, open side facing up.
In a small bowl, mix together 2 Tbsp. olive oil, garlic, ½ tsp. dried thyme, and a little salt and pepper to taste.
Drizzle over the inside of each mushroom evenly. Top each with a thin slice of dairy free butter from ½ a Tbsp.
Bake the mushrooms for around 15 minutes until tender. While they are cooking, mix together the 1 Tbsp. grated dairy free Parmesan and 3 Tbsp. dairy free shredded Mozzarella.
After the 15 min, top the mushrooms with the dairy free cheese and return to the oven for around 5 minutes. Once the cheese is golden and bubbly, remove the mushrooms from the oven, serve, and enjoy!