Soak half of the raisins in either Cognac or rum for at least one hour. Preheat oven to 325 degrees F., and line a cookie sheet with parchment paper.
Coarsely chopped the remaining raisins, and mix them together with flour, baking powder, baking soda, and salt.
Cream softened butter and sugar in another bowl until light and fluffy. After adding eggs, egg whites, and vanilla extract, continue beating to blend them well.
Stir in the soaked raisins. Then gradually add the flour mixture. Fold in chopped walnuts.
Turn dough out onto a lightly flour surface. If it is too sticky, add some flour for easy handling.
Divide dough in half. Shape each half into a log about 12 inches long and 2 inches wide. Then place them at least 2 inches apart on prepared cookie sheet.
Bake for about 30 minutes until logs are light golden in color and firm to touch. Cool them slightly on wire racks for about 5 minutes.
Reduce oven to 250 degrees F., then slice each log diagonally into ½-inch slices. Arrange rusks, cut side down, on a cool cookie sheet.
Bake again for about 30 minutes, turn them over, and continue baking for another 30 minutes. Note: all baking time is approximate and depend on individual oven.
Cool sukhariki on wire racks before storing them in an airtight container. They will keep for a month at room temperature.
