Heat a little oil in a pan and sweat the mushrooms, thyme and chopped onion together for about 5 minutes. Season with salt, pepper and garlic powder. When ready, turn off the heat and set aside.
In a bowl, mix the flour, baking powder, baking soda, oil, vinegar, and soy milk and mix to obtain a uniform batter.
Add the sauteed mushrooms, parsley, and vegan mozzarella to the batter and mix.
Arrange silicone molds over a baking tray, and pour into each bowl 2-3 tablespoons of the batter. Garnish with a little parsley on top.
Bake in the oven for 20-30 minutes, depending on your oven, check at the end of baking if it is ready with a toothpick in the center of the muffin. If the toothpick is not wet it is ready. You may have bits of melted cheese and that's fine.