1. Preheat the oven to 190°C (375°F).

2. Melt 15g (1 tablespoon) of butter in a large skillet over medium heat. Add the garlic and sauté for 1 minute.

3. Add the mushrooms and cook until tender, about 5 minutes. Add the cognac and cook until the liquid is almost completely evaporated. Season with salt and Tabasco. Set aside.

4. In a separate skillet, melt the remaining 15g (1 tablespoon) of butter over medium heat. Add the shrimp and cook until pink and just cooked through, about 2-3 minutes per side. Remove from heat and set aside.

5. Combine 250ml (1 cup) of heavy cream, 60ml (1/4 cup) of white wine, and 60g (1/2 cup) of flour in a large saucepan. Whisk until smooth and cook over medium heat, stirring constantly, until the mixture thickens, about 5 minutes.

6. Remove from heat and stir in 120g (1 cup) of grated Parmesan cheese until melted. Season with salt to taste.

7. Arrange half of the mushroom mixture in the bottom of a greased 23x33cm (9x13-inch) baking dish. Top with half of the shrimp, half of the lobster meat, and half of the cream sauce. Repeat the layers, finishing with the cream sauce on top.

8. Sprinkle chopped parsley and chives over the top of the gratin.

9. Bake in the preheated oven for 20-25 minutes or until the top is golden brown and the sauce is bubbly. Serve immediately.