To prepare a walnut and chocolate tassies baked goods recipe, first you need to prepare the ingredients for the recipe. First, you'll need the following ingredients: Preheat the oven to 375 degrees F. Line two 9x9-inch baking pans with parchment paper. Set aside. In the bowl of an electric mixer, cream together the butter and sugar until light and fluffy. Add the egg and vanilla and beat until combined. Gradually add the flour and mix until just combined, scraping down the sides of the mixing bowl as you go. Pour the wet ingredients into the dry ingredients, mixing just until the batter is smooth. Stir in the walnuts until they're evenly coated. Press the mixture evenly onto the greased and floured baking sheets. Bake the cookies for 20 to 25 minutes, or until toothpick inserted in center comes out clean. Allow to cool before cutting into squares. Serve warm or at room temperature.