In a food processor fitted with a chopping blade, process the almonds and 3 tablespoons of the sugar until the almonds are finely ground. Set aside.

In a mixing bowl, beat butter and remaining ¾ cup of sugar on medium speed until the mixture is light in color and texture, at least 3 minutes. Beat in the egg, vanilla extract, baking powder, and salt until well blended. Add the almond mixture, blending just until smooth. On low speed, gradually beat in the flour mixture just until smooth. Cover the dough tightly with plastic wrap. Refrigerate until the dough is thoroughly chilled, at least 2 hours or up to 5 days.

Preheat the oven to 350° F. Line two large baking sheets with parchment paper. Using 1 teaspoon for each, portion the dough into 80 pieces. Roll the dough into small balls; place about 1½ inches apart on the prepared baking sheets. Bake in center to top third of the oven until the cookies are lightly browned all over, 10 to 12 minutes. Let the cookies cool on the baking sheets for 3 minutes. Carefully transfer to wire cooling racks and cool completely.

In the top part of a double boiler over hot, not simmering, water, melt the chocolate. Using a small icing spatula or knife, spread about ½ teaspoon on the underside of a cookie, then sandwich with another cookie, placing them back to back. When the chocolate has cooled and set, store cookies at room temperature in an airtight container. NOTE: Omit the chocolate filing to make an excellent wafer-type cookie. Yield: 40 cookies.

*Pecans can be used in place of almonds. If whole almonds with skin are used, blanch to remove the skins. To blanch, pour boiling water over almonds. Let stand for three minutes. Slip the skins off. To toast the nuts, spread them on a baking sheet. Bake in a preheated 350° F oven for about 10 minutes. Processing the nuts with sugar keeps them from releasing too much oil from the blade's friction.