Preheat the oven to 350 degrees F (175 degrees C) and line a 12 well muffin tin with paper liners.
In a small pot, bring the Vegetable Stock (1 cup) to a low boil.
Stir in the Quinoa (1/2 cup). Cover the pot and let it simmer on medium low for 12 minutes, until the quinoa is tender. You should see little tendrils coming out of it. Fluff it up using a fork and then let it cool completely off of the heat.
Whisk the Egg (1), Milk (1/2 cup), and Olive Oil (1/2 cup) together in another bowl for the wet ingredients.
When the quinoa has cooled, add it to the bowl of Oat Flour (1 1/2 cup).
Add the Worcestershire Sauce (1 dash), Salt (1 pinch), Crushed Red Pepper Flakes (1 pinch), and Ground Cumin (1 pinch) to the bowl with the quinoa. Whisk it all together.
Pour in the wet ingredients and stir it all together well until it is a uniform batter. Fold in the Celery (1 stalk), Cremini Mushroom (4 ounce), and Fresh Baby Spinach (1/2 cup) to finish it up.
Scoop a 1/4 cup of batter into each well of the prepared muffin tin.
Bake the cakes for 20-25 minutes. They should be slightly crisp and golden on top and around the edges but still tender in the middle.
Let them cool when they are done, then serve!