Preheat oven to 350°F.
Beat butter with an electric mixer until creamy. Gradually add sugar and mix well. Add egg and beat well. Add almond extract, lemon zest and fennel seeds; mix to combine.
Finally mix in flour, ground almonds, baking powder and salt. Beat well. Stir in the pistachios. This will make a stiff dough.
Shape dough into 1-inch balls; place 2 inches apart on an ungreased baking sheets. If desired, flatten balls slightly and sprinkle with additional chopped pistachios.
Bake for 10 minutes or until lightly browned. Cool slightly on baking sheets; remove to cooling racks and cool completely.
Store in an airtight container at room temperature for up to 1 week. Inspired by a food.com recipe.
