Poppy Seed Slices

1 cup butter or margarine, softened
3/4 cup sugar
1 egg
1 teaspoon vanilla
2 cups flour
1/2 cup finely ground blanched hazelnuts or almonds
1/2 cup poppy seed

1/4 teaspoon salt

Beat butter until fluffy, beat in sugar, egg, and vanilla. Mix in combined flour, nuts, poppy seed, and salt. Divide dough into 2 equal parts, shape each into a roll 1 1/2 inches in diameter. Wrap in waxed paper and refrigerate until form, about 4 hours. Cut rolls into 1/4-inch slices and place on ungreased cookie sheet. Bake at 325° until edges are beginning to brown, about 15 minutes. Cool on a wire rack.