Melt butter in a large saucepan over medium heat. Add shallot and garlic. Sauté briefly, do not brown. Add shrimp, scallops and fish pieces. Sauté until slightly opaque. Remove and reserve. Add mushrooms and scallions to pan and sauté. Deglaze with Brandy and reduce by 1/2. Add white wine, simmer and reduce by 1/2. Add fish stock and tarragon bring to a simmer and reduce heat. Simmer for 3 - 4 minutes. Finish with cream. Return seafood to sauce. Add parsley and season with a squeeze of lemon, salt and pepper. Place “bottoms” of puff pastry onto warm serving plates. Top each with seafood and sauce. Place “tops” over seafood and serve immediately.