Cub Foods and Treasure Island reliably stock these cookies and as PBandFluff notes, they are often shelved with ice-cream toppings at other stores.
However, Flip is absolutely correct that Oreos work just as well if you're going to be crushing them to crumbs. (My usual method is to unscrew the cookies, set aside the half to which the filling adheres for eating open-face, and use the other half in the recipe. Although I've seen many recipes that just call for crushing the cookies, filling and all (
Chocolate cream pie with Oreo crust).
Alternatively, you can bake your own. These will be lighter in color than the commercial version. Add brown paste food coloring for darker cookies.
Chocolate wafer cookies
3/4 cup Dutch-process cocoa powder
3/4 cup all-purpose flour
1/4 teaspoon salt
4 tablespoons (1/2 stick) unsalted butter, at room temperature
1/2 cup light brown sugar
1/2 cup granulated sugar
1 teaspoon vanilla extract
2 egg whites
Sift the cocoa with the flour and salt; set aside. In the large bowl of an electric mixer, beat the butter, brown and granulated sugars and vanilla on medium speed about 5 minutes. Beat in the egg whites, one at a time.
Scrape down bowl and beaters and add the cocoa mixture, mixing on low speed until well combined.
Remove the dough from the bowl, divide in half, and using plastic wrap to help, shape into logs 2 inches in diameter. Refrigerate till firm, several hours or overnight.
Preheat the oven to 350 degrees. Line 2 cookie sheets with parchment or foil. With a sharp knife, cut the dough into slices about 1/8 inch thick. (Alternatively, roll the dough out thinly on a lightly floured work surface. Cut the dough with a 2-inch round cutter. You can press the scraps together and re-roll to make more cookies.)
Place the cookies on the prepared pans. Pierce the cookies several times with a fork. Bake 20 minutes, until lightly puffed and firm. Let cool on the pan, and then peel off the paper or foil. About 3 dozen cookies.
Here are two recipes using wafer cookies:
Mary Jane Calin's ice-box cake
1/2 pint whipping cream
Sugar to taste
1 9-ounce package chocolate wafers
2 medium ripe bananas, peeled and sliced
1 8-ounce can crushed pineapple (drained)
In the large bowl of an electric mixer, whip the cream until stiff, adding sugar as desired.
Place one layer of cookies on a plate. Add one layer of sliced bananas. Over that layer some of the pineapple. Then cover the top with a thin layer of whipped cream.
Repeat the layers until only one layer of the cookies is on the top. Then cover the top and sides of the cake with the remaining whipped cream. Refrigerate several hours. 8 servings.
Chocolate cherry terrine
1 cup mascarpone cheese
1 1/2 cups whipping cream
1/2 cup powdered sugar
1 tablespoon vanilla extract
2 1/2 cups morello cherries in syrup
Kirsch to taste (optional)
1 9-ounce box chocolate wafer cookies
10 maraschino cherries with stems for garnish
In the large bowl of an electric mixer, combine the mascarpone, whipping cream, powdered sugar and vanilla and beat to soft peaks. Cover and chill until ready to use.
Drain the morello cherries in a strainer and reserve the juice. Add a little kirsch to the syrup if desired.
Line a 10-by-4 1/2-by-3-inch loaf pan with plastic wrap. Cover the bottom with a layer of overlapping chocolate wafers -- about 12. Drizzle the cookies with about 1/4 cup of the cherry syrup. Spread 1/2 cup of the mascarpone mixture evenly over the cookies. Top with half the drained cherries and spread another cup of the cheese mixture over them.
Top with about 12 more cookies and drizzle heavily with the syrup. Spread another 1/2 cup of the cheese mixture over the cookies, top with the remaining cherries and spread with another cup of the cheese. Add the remaining cookies and drizzle heavily with syrup.
Cover the pan with plastic wrap and chill for 8 hours or overnight. Cover the remaining cheese mixture and place in the refrigerator.
Invert the loaf pan onto a serving plate. Lift off the pan and plastic wrap. Fill a pastry bag fitted with a star tip with the remaining cheese mixture and pipe a decorative squiggle down the center. Garnish with the stem cherries. 10 servings