First, heat the oil in a large heavy-bottom skillet over medium heat.
Meanwhile, in a small bowl, whisk the stock and cornstarch.
Next, add the mushrooms in a single layer and cook undisturbed for about 2-3 minutes, then stir and continue to cook for 1-2 minutes more. You might have too cook them in batches, to avoid overcrowding the pan.
Once all mushrooms are slightly tender and golden, add the garlic and cook until fragrant, for 1 minute.
Then, add the stock-starch mixture together with the almond milk and season with salt and pepper.
Stir until sauce begins to thicken, about 3-4 minutes.
Finally, add in the shredded cheeses. Continue to cook until cheese is fully melted, then stir in the herbs and take off the heat.