For crust: In a medium bowl, combine Parmesan, bread crumbs, and melted butter. Press Parmesan mixture into the bottom of a 9-inch springform pan. Set aside.
In a medium skillet, cook onion and sweet peppers in hot oil over medium heat for 2 minutes. Add salt and black pepper. Cook and stir for 1 minute more. Remove from heat; set aside.
For filling: In a large mixing bowl, beat cream cheese and Gouda with an electric mixer until smooth. Add eggs; beat just until combined. Do not overbeat. Stir in the onion mixture, crawfish tails with juice or shrimp and whipping cream.
Pour filling into crust. Bake in preheated oven for 1 to 1-1/4 hours or until center appears nearly set when shaken. Cool on a wire rack for 1 hour. Cover; chill at least 2 hours or up to 24 hours in the refrigerator.
To serve, remove sides of pan. With a warm knife, cut into wedges. Serve with crackers or toasted baguette slices.