Alton Brown has a good recipe for homemade vanilla wafers that uses 7 ounces all purpose flour, 3/4 teaspoon baking powder, 1/2 teaspoon salt, 4 ounces unsalted butter and 3 1/2 ounces vanilla sugar. One large egg, 4 teaspoons vanilla extract and 1 tablespoon whole milk are also required.
The first step in making the vanilla wafers involves sifting the flour, baking powder and salt into a small bowl. Using a stand mixer, cream the butter and vanilla sugar together on medium speed for 2 minutes. Add the egg, and mix for 30 seconds. Then add the vanilla and milk, and mix on low speed for 15 seconds. The last step is adding the flour mixture and mixing on low speed until incorporated.
It's best to chill the dough in the refrigerator for at least 10 minutes before forming the cookies. After chilling, use a teaspoon to scoop the batter into balls and place on a cookie sheet lined with parchment paper. Placing about 35 cookies per half sheet pan is recommended. Flatten the balls slightly, then bake for 15 to 20 minutes in an oven preheated to 350 degrees Fahrenheit. After baking, it's best to place the pan on a cooling rack and allow the cookies to cool completely before removing them from the pan.