My father's side of the family are Pennsylvania Dutch (German). There are many recipes I could post.
Here's one of my favorites.
MAKES 3 DOZEN COOKIES
3-1/2 cups all-purpose flour
1-1/2 cups unsweetened cocoa powder
1 teaspoon salt
1 tablespoon baking soda
1 teaspoon baking powder
1 cup (2 sticks) butter, softened to room temperature
2 cups granulated sugar
2 large eggs
2 cups buttermilk (see notes below)
2 teaspoons vanilla
Seven Minute Cream Filling
2 large egg whites
1-1/2 cups granulated sugar
Pinch of salt
1 teaspoon light corn syrup
1/4 teaspoon cream of tartar
5 tablespoons cold water
1 teaspoon vanilla
For the cookies: Preheat oven to 400° F. Line 2 large baking sheets with parchment paper. Into a large bowl, sift together the flour, cocoa, salt, baking soda, and baking powder. In another large bowl, cream the butter and sugar with an electric mixer until light and fluffy. Add the eggs, buttermilk and vanilla; beat until well-combined. Gradually add the dry ingredients, mixing after each addition until combined. Drop batter onto sheets by heaping tablespoons, about 3 inches apart, as they will spread. (I use a small scoop that is about a one tablespoon capacity. It makes dropping the batter much easier and more uniform.) Bake for about 12 minutes, or until the tops of the cookies spring back to the touch. Let cool slightly before removing to a cooling rack topped with parchment or waxed paper. Let cool completely. Meanwhile, make the filling.
For the filling: Place the eggs, sugar, salt, corn syrup, cream of tartar and cold water in a medium heatproof bowl or the top of a double boiler. Beat with a handheld electric mixer just until combined. Place the bowl over a pot of boiling water, being very careful to make certain that the bottom of the bowl is not touching the water. Beat with the mixer on high speed for 7 minutes. Remove from the pan and add the vanilla. Beat again until combined. To speed up the cooling process, place the bowl in a larger bowl of ice and water. Continue to beat until the filling is thick and cool.
To assemble: Spread cooled filling, about 1-1/2 tablespoons per cookie, on the bottom of half of the cookies. Top each with the remaining cookies. Sandwiches may be served immediately. If storing, wrap individually with plastic wrap or waxed paper, then place in storage bags. Store in the refrigerator for several days, or freeze in freezer bags for several months.
Here's an image I found on the internet but looks exactly like the kind my grandmother used to make when we were kids.
I will make some and post pics some day.