1. Preheat oven to 425 degrees.

2. Place clams in a 4-quart pot and add 1 cup white wine or water; cover and cook over medium-high heat until clams have opened, about 5 minutes. Remove from heat; let cool.

3. Meanwhile, rinse spinach with cold water; shake to remove excess water but do not pat dry. Place spinach in a medium saucepan; cover and cook over medium heat until spinach is wilted, 8 to 10 minutes. Uncover, stir, and cover again; continue cooking 2 minutes more. Drain and let cool slightly. Squeeze spinach to remove excess moisture; chop and set aside.

4. Remove clams from shells, reserving shells and discarding any clams that remain unopened. Finely chop clams; you should have about 1 1/2 cups. Set aside. Line a fine mesh sieve with cheesecloth and set over a medium bowl; strain clam cooking liquid into bowl and set aside 1/2 cup. Reserve any remaining liquid for another use.

5. Melt 4 tablespoons butter in a large skillet over medium heat. Add shallots, garlic, and celery; cook, stirring, for 5 minutes. Add remaining 3 tablespoons wine and bring to a simmer; cook until liquid is almost evaporated. Add reserved spinach and clams; stir to combine.

6. Cut remaining 8 tablespoons butter into pieces and add to skillet along with parsley, tarragon, chives, breadcrumbs, reserved clam juice, and anise. Add egg yolk and stir to combine; season with salt and pepper. Cook, stirring occasionally, about 3 minutes. Fill reserved clam shells with clam mixture; transfer shells to a baking sheet and sprinkle with cheese. Bake until filling is hot, about 10 minutes. Serve immediately with lemon wedges.