1. Preheat your oven to 390°F or 200°C.

2. Heat a generous amount of olive oil in a large skillet over medium-high heat and cook the chicken until it's nicely browned on both sides. Add salt and pepper to taste, then set it aside for the time being.

3. Cut the bacon into thin strips and cook them in the same skillet until they're crispy and golden. Remove the bacon from the skillet with a slotted spoon and drain on paper towels, reserving a few strips for garnish.

4. Finely chop the garlic and onions, then sauté them in the same skillet until they're softened and lightly browned. Add the cooked bacon, chicken, dried oregano, salt, and pepper to the skillet, and stir everything together well.

5. Peel the potatoes and slice them into 1/2-inch or 1.3 cm thick rounds. In a large baking dish, create alternating layers of potatoes and the chicken mixture, starting and ending with a layer of potatoes.

6. In a small bowl, mix the fresh cheese with heavy cream until it's smooth and creamy. Pour the cheese mixture over the top layer of potatoes, then sprinkle grated cheddar cheese over the top.

7. Place the baking dish in the middle of the oven and bake for 30-40 minutes, or until the potatoes are tender when pierced with a fork.

8. Remove the gratin from the oven and garnish it with fresh arugula and the reserved crispy bacon.