Preheat the oven to 425° F.
Prepare a baking sheet with parchment paper and set aside.
Slice up the fresh mushrooms and onion (if using fresh).
In a large skillet with oil, saute the mushrooms, onion, and garlic.
Once the mushrooms are done, remove from the heat and set aside.
Next, in a medium sized sauce pan, add water, flour, seasonings, and maple syrup, blend until combined, making sure there are no lumps.
Bring everything to a boil, then stir in the oats.
Turn the heat down to low and continue cooking for about 2 to 3 minutes.
The mixture will be thick enough to form into a burger.
Next add the sauteed mushrooms to the oats mixture until well combined.
Remove from the heat, set aside to cool for about 30 minutes.
Once the mixture is cool to the touch, add everything to a food processor.
Pulse until the mushrooms are into small pieces, similar to the size of a pea.
After all the mushrooms are chopped, scoop up the mixture with about 1/3 cup and place onto the prepared baking sheet.
Spread each scoop into burger patties.
Once the baking sheet is full, place it into the oven.
Bake the burgers for about 20 minutes.
Remove the baking sheet from the oven, flip the burgers, and return the baking sheet to the oven.
Bake for additional 15 to 20 minutes.
Check the burger to make sure they are firm, if not return to the oven for an additional 5 minutes until the burgers are firm.
Once the burgers are done, remove from the oven to cool or serve.
