This is the only recipe I have which might be close - its very good!

CLAMS CASINO

Posted by tobygirl on Sun, Dec 23, 07 at 6:31
Here's a very good one, which I have made many times.

2 cans minced claims with their liquid
2 Tbls. lemon juice
1 small onion chopped
2 cloves garlic minced
2 Tbls. fresh parsley chopped or 1 tsp. dried
1/4 c. butter
1/2 tsp. oregano
3/4 c. seasoned bread crumbs
2 drops hot sauce or to taste
1/2 c. cheddar or parmesan cheese grated
Paprika

Preheat oven to 350 degrees. Simmer clams with their liquid and lemon juice in a covered saucepan for 5 minutes. Set aside. Saute onion, garlic and parsley in butter for about 5 minutes; then add the oregano, bread crumbs, hot sauce and clams/lemon juice mixture. Spoon into a greased pie plate and bake for 20 minutes. Sprinkle with the grated cheese and paprika and return to oven just until cheese melts. Serve warm with crackers.

Here's another!

Ritz Cracker Clam Casserole
Ingredients

1/2 c margarine, melted .
34 Ritz crackers, crushed .
salt & pepper .
lemon juice, to taste .
6 1/2 oz minced clams (fresh lobster, langastanos, scallops, shrimp, or fresh white fish may be substituted)

Directions

Step #1 Crush crackers.
Step #2 Mix clams or other seafood & crackers together.
Step #3 Put in small individual casserole dishes of your choice.
Step #4 The amount this will serve, depends on what size you use.
Step #5 I use about 8"x3" individual casserole dishes.
Step #6 Divide the seafood mixture between the casserole dishes.
Step #7 Add melted butter over the top of each casserole dish.
Step #8 Squirt desired amount of lemon juice over top.
Step #9 of all.
Step #10 Sprinkle top with desired amount of salt & pepper.
Step #11 Bake for 25 mins at 325.

Here's one that I can absolutely recommend, even though I've never made it. It is from DOWNEAST COOKING by Marjorie Standish. She was the food editor for the Maine Sunday Telegram for many years (this cookbook is from 1969) and her recipes are as authentic as you would ever hope to find.....

Clam Casserole
1 can minced clams
30 salty crackers, crushed
2 eggs beaten
1 cup milk
1 can cream of mushroom soul
1/4 cup melted butter or margarine.

Beat the 2 eggs slightly. Add cream of mushroom soup, milk crackers , clams and butter. Turn into a greased 1 1/2 qt casserole. Bake at 350 degrees for 1 hour. I like to place any casserole which uses eggs and milk into a pie plate, with 1/2 inch hot water in the plate. It helps to prevent curdling.

I was going to suggest the Marjorie Standish cookbook also. I believe she has several clam casserole recipes.
And since your grandmother was from Boston I bet she got this recipe from the COOKING DOWNEAST COOKBOOK.
Just google her name or the cookbook name and I bet you can find what you are looking for.

I have the recipe you were asking about. My ex-sister-in-law is a corporate executive of Nabisco, and that is where the recipe originated from. She always made it for the holidays when she came to visit (she lived near Boston at the time!) because she always got 'free' crackers!

Following is the recipe. No added ingredients, just plain and simple.

2 cans chopped clams, with juice.
1 can chopped clams, drained.
1 pound bacon, cooked and crumbled.
1 green pepper, finely chopped.
1 onion, finely chopped.
1 roll Ritz crackers, crumbled.

Mix all ingredients and bake uncovered for 30 minutes at 375 degrees. Serve with crackers.

Thank you everyone for sharing thse recipes. I will have a great time testing them all!