Separate the salmon into individual slices.

Heat butter in a medium skillet and sauté the salmon until it is done, turning once, for just a minute or so. You can skip this step if you prefer to use the salmon uncooked.

Break the salmon into pieces. If you aren't cooking the salmon, cut it into pieces with a sharp knife.

In a medium bowl, beat cream cheese with an electric mixer until soft and fluffy.

Beat in mayonnaise until smooth.

Stir in the salmon and dried basil.

Make sandwiches with the salmon filling, the whole basil leaves, and croissants.

Serve immediately. You can make the filling ahead of time; just cover it well and store it in the refrigerator up to 3 days.