1. Preheat the oven to 200°C (400°F).

2. In a large skillet over medium-high heat, melt 15g (1 tablespoon) of butter. Add the beef strips and cook until browned, about 3-4 minutes. Remove and set aside.

3. In the same skillet, melt the remaining 15g (1 tablespoon) of butter. Sauté the chopped onion until soft, about 5 minutes. Stir in the minced garlic and cook for 1 more minute.

4. In a large bowl, mix the cooked beef, onion mixture, sliced potatoes, chopped red chili pepper, salt, and black pepper. Toss until well combined.

5. Grease a 23x33 cm (9x13 inch) baking dish. Arrange a layer of overlapping potato slices on the bottom. Spread a layer of the beef mixture on top, followed by a scattering of fresh spinach leaves. Repeat the layers until all ingredients are used, ensuring the final layer is potatoes.

6. Dot the top with small pieces of softened butter. Bake for 45-50 minutes, until the potatoes are golden and the filling is hot and bubbling. In the last 10 minutes of baking, scatter the cherry tomatoes on the vine over the top.

7. Remove from the oven and sprinkle with chopped fresh parsley. Serve immediately while hot, using a spatula to carefully lift out portions, as the dish will be very hot. Enjoy this comforting, flavorful meal with your loved ones.