Prepare mushrooms: Clean and cut the mushrooms into large pieces. Heat olive oil in a frying pan over high heat until very hot.
Sauté mushrooms: Add mushrooms to the hot oil without stirring initially. Let them fry and caramelize on high heat until they start to brown.
Add onions: Sprinkle cut onions over the mushrooms without stirring to allow mushrooms to continue caramelizing.
Add garlic and ouzo: Melt garlic cloves in the pan, then add ouzo to deglaze and infuse flavor.
Season and caramelize: Add a pinch of sugar, paprika, and dried oregano. Stir gently and continue cooking to enhance caramelization.
Prepare tomatoes: Peel and grate ripe tomatoes into a bowl. Add tomato paste to thicken the sauce.
Combine tomatoes with mushrooms: Add the grated tomatoes and tomato paste to the pan. Stir to combine and cook for a few minutes to thicken the sauce.
Add feta cheese: Mix small pieces of feta cheese into the sauce to melt slightly. Then add larger pieces on top.
Bake the saganaki: Preheat oven to 230°C (450°F). Transfer the pan to the oven and bake for 10-15 minutes until the feta cheese is browned and the sauce is firm.
Serve: Remove from oven, sprinkle with chopped parsley and freshly ground black pepper. Serve warm, optionally with bread.