Step 1

In a large mixing bowl, whisk flour, baking powder, salt and yeast. (see notes if using active yeast instead of instant yeast)

Step 2

Using a pastry cutter or two knives, cut the butter into the flour mixture until no pieces are larger than a pea. Set aside.

Step 3

In a small mixing bowl, whisk together the egg yolks, water, sour cream and vanilla.

Step 4

Make a well in the flour mixture and pour the egg yolk mixture into the center. Mix with a large, sturdy spoon until the dough comes together and wet ingredients are distributed. Dough will look shaggy.

Step 5

Use your hands to finish the mixing process insuring all dry bits in the bottom of the bowl have been incorporated and you can form a ball.

Step 6

Wrap ball in plastic wrap and refrigerate for 1 hour.

Step 7

In a stand mixer, using the whip attachment, whip egg whites until foamy and no longer transparent. Very gradually add the sugar while continuing to whip. Whip to stiff peaks. This may take from 7-10 minutes.

Step 8

Fold in nuts and almond extract.

Step 9

Preheat oven to 400 degrees F. Line 2 large sheet pans with parchment. Set aside.

Step 10

Remove dough from refrigerator and divide into 4 pieces.

Step 11

Sprinkle confectioner's sugar on work surface and rolling pin. Roll one piece of dough into a 9" circle adding confectioner's sugar as necessary to prevent sticking. Cut into 12 equal "pie" slice wedges. Don't worry about imperfect edges. The wide end is simply going to be rolled up into the inside and won't be visible. (You can continue rolling and cutting all four sections of pastry before moving onto the filling step.)

Step 12

Take a quarter of the meringue mixture and spread it over the entire circle of cut dough.

Step 13

Lift the edge of one wedge and pull it away from the circle. Gently roll it from the wide end to the point, taking care not to squeeze all of the meringue out from the roll. Set it, with the point side down onto the prepared baking sheet.

Step 14

Repeat process with remaining wedges and remaining pieces of dough, placing cookies about 1 1/2" apart on the baking sheet.

Step 15

Bake for 10-12 minutes or until cookies are puffy and light golden brown on top.

Step 16

When cool, dust with confectioner's sugar and serve. Store in an airtight container for up to 3 days.