Mazurek Wilenski (Vilnian Mazurka) - cooking recipe

Ingredients

Dough
2/3 cup butter, softened
2 3/4 cups flour, sifted
2/3 cup powdered sugar
2 teaspoons baking powder
1 egg
1 egg yolk
3 tablespoons sour cream
1 tablespoon butter, softened
2 tablespoons flour
Filling
6 egg whites
3 3/4 cups powdered sugar
8 ounces powdered cocoa mix
8 ounces almonds, ground
8 ounces dates, pitted & finely sliced
Icing
2 cups powdered sugar
3 tablespoons rum

Preparation

To prepare dough: use a knife to cut the butter into the flour, then rub it in with your fingertips.
Add the powdered sugar, baking powder, egg, egg yolk, and sour cream; mix together.
Knead with your hands until dough is smooth and can be formed into a compact ball.
Wrap in waxed paper or place in a covered dish and refrigerate for at least 1 hour.
Preheat oven to 375\u00b0F.
Grease a 12\"x15\" cookie sheet with the remaining tablespoon of butter; sprinkle with remaining 2 tablespoons of flour, tipping from side to side to cover completely and evenly.
Turn the sheet upside down and tap on the bottom to shake off any excess flour.
On a lightly floured surface, roll dough out to 1/4\" thin and place on buttered cookie sheet, using fingers to spread dough so it completely covers the bottom of the pan.
Bake for 10 minutes.
To prepare filling: beat egg whites until stiff.
Add sugar a few tablespoons at a time, beating constantly.
Once all of the sugar has been added, beat for 5 more minutes.
Fold in the chocolate, almonds, and dates.
Spread over the dough layer.
Bake at 350\u00b0F until pastry is golden brown (20-25 minutes).
Allow to cool.
Mix sugar with rum until smooth; drizzle mixture over mazurka.
With a lightly buttered knife, cut into squares.