Preheat the oven to 375°F.

Cook the jumbo pasta shells according to package instructions until al dente. Drain and set aside to cool slightly.

In a mixing bowl, combine the ricotta cheese, 1/2 cup mozzarella cheese, 1/4 cup Parmesan cheese, chopped basil, lemon zest, lemon juice, garlic powder, salt, and pepper. Mix until well combined.

Stuff each cooked pasta shell with the ricotta mixture and place them in a greased 9x13 inch baking dish.

In a saucepan, heat the olive oil over medium heat. Add the heavy cream and champagne, stirring to combine. Bring to a gentle simmer and cook for about 5 minutes, allowing the sauce to thicken slightly. If using, add red pepper flakes for a bit of heat.

Pour the champagne cream sauce over the stuffed shells, ensuring they are well covered. Sprinkle the remaining mozzarella and Parmesan cheese on top.

Cover the baking dish with aluminum foil and bake for 20 minutes. Remove the foil and bake for an additional 10 minutes, or until the cheese is bubbly and golden.

Let the dish cool for a few minutes before serving.