Heat 2 tbsp of olive oil in a saucepan. Add the ground beef, the onion, the tomatoes, salt, black paper, oregano. Cover and cook on low heat, stirring occasionally until the liquids from the tomatoes are almost evaporated and the mixture become dry.
Preheat oven to 375°F Spray the bottom of a square baking pan. Arrange 2 sliced potatoes on the bottom of the pan, sprinkle with salt and black paper, cover with ground beef mixture and cover with the remaining potato slices. Sprinkle with salt and black paper. Add 1/2 cup white wine and 1/2 cup water. The liquid must almost cover the last level of potato slices. Pour into the preheated oven and bake about 45 minutes or until the liquid is evaporated. If the potatoes start to burn too much and the liquid is not evaporated yet, cover with baking paper.
Meanwhile, in a small mixing bowl beat eggs, add milk and the flour. Add salt, black paper, fresh parsley or dry oregano. Pour over the already dried moussaka. Bake 5 more minutes or until the top is golden brown and crispy. Serve warm.