Cookies:
1 cup butter, softened
1/2 cup granulated sugar
2 teaspoons finely shredded lemon peel
1/4 cup lemon juice
1 teaspoon vanilla
2 1/4 cups all-purpose flour
3/4 cup finely chopped Brazil nuts or hazelnuts (filberts)

Lemon Butter cream Frosting:
3 tablespoons softened butter
3 cups powdered sugar
1 teaspoon finely shredded lemon peel
2 tablespoons lemon juice
1 - 2 tablespoons whipping cream