Process first 8 ingredients in a blender or food processor until smooth; set pesto aside.
Bring wine, chopped garlic, and shallot to a boil in a Dutch oven. Add clams, and cook 5 minutes or until clams open. Drain and cool.
Remove clams from shells, reserving 40 half shells. Chill clams at least 1 hour.
Stir pesto into clams; spoon 1 clam and pesto into each reserved shell. Garnish, if desired.