Marinate chicken with oyster sauce, black pepper, salt, chili flakes, and ginger garlic paste.
In a pan, heat oil and add marinated chicken. Cook until it starts to brown.
Add sliced mushrooms and sauté until tender.
Stir in heavy cream and a pinch of oregano. Let it simmer for 2–3 minutes. Set aside.
In a saucepan, melt butter and add flour. Cook for a minute to remove the raw taste.
Gradually whisk in chicken stock and milk until smooth and lump-free.
Add cheddar cheese and stir until melted.
Season with black pepper, garlic powder, chili flakes, and oregano. Simmer until thickened.
In a deep baking dish, start with a layer of white sauce.
Add a layer of lasagna strips, then a thin layer of white sauce.
Spoon over the chicken and mushroom base, followed by a generous layer of white sauce.
Add sliced olives, then repeat the layering.
For the final layer, add lasagna strips, top with a generous amount of white sauce, cheddar cheese, and finish with mozzarella.
Sprinkle oregano on top.
Preheat oven to 180°C (350°F).
Bake uncovered for 25–30 minutes or until the top is golden and bubbly.
Let it rest for 10 minutes before serving.