Preheat your oven to 180°C (350°F) and line a small baking dish with parchment paper.
In a medium mixing bowl, combine the ground chicken breast, oat flour, olive oil, garlic powder, onion powder, oregano, sea salt, and black pepper.
Mix the chicken and oat mixture thoroughly until a uniform dough-like consistency forms.
Press the chicken mixture firmly and evenly into the bottom of the prepared baking dish to create a solid base.
Bake the chicken base for 10 minutes until it is opaque and starting to set.
While the base is baking, whisk together the cottage cheese and the egg in a separate bowl until well combined.
Remove the baking dish from the oven and spread the cottage cheese mixture evenly over the chicken base.
Arrange the sliced cremini mushrooms in a single layer across the top of the cottage cheese.
Return the dish to the oven and bake for an additional 10-15 minutes until the topping is set.
Increase the oven temperature to 220°C (425°F) for the final 3-5 minutes to achieve a golden-brown, crispy finish.
Remove from the oven and garnish with fresh chopped parsley before slicing and serving.