Preheat oven to 400F (200C).
Prepare an oven tray with parchment paper.
Set a pan over medium heat (with a bit of oil or water), and sauté the onions until translucent. Then add the parsley. When both are ready, set aside.
In a bowl place the beans and mash them.
Add the rest of the ingredients and mix well.
Form the patties with your hands and place them in the oven tray (you can also lightly brush them will olive oil, as an optional step, especially if you are not using parchment paper or cooking them on the stove). Additionally, you can place the patties in the fridge for about 30 minutes or 1 hour before cooking them; this helps them retain their shape better.
Bake the patties until they are golden outside for about 35 minutes, flipping them halfway.
You can serve them with buns and favorite toppings. Or accompanied with a salad of your choice.