In the bowl of a stand mixer, cream 454 grams of softened butter for about 30 seconds until slightly fluffy.

Mix in 1/3 cup of granulated sugar, beating for approximately 1 minute, or until the mixture is light and fluffy.

Add in 2 egg yolks and 500 mL of sour cream, mixing until well-blended.

Switch to 'stir mode' and gradually add in 4 cups of all-purpose flour and 1/4 teaspoon of salt. Mix until the dough is just combined.

Split the dough in half, and then each half into 4 pieces, for a total of 8. Wrap each piece in cling wrap and refrigerate for at least 2 hours or overnight.

In a food processor, pulse together 1 1/4 cups of walnuts, 1 1/4 cups of granulated sugar, and 3 teaspoons of cinnamon until finely blended. Divide this mixture into two bowls for later use.

Work with one piece of dough at a time on a lightly floured surface. Roll it out into a 10-inch round circle.

Brush the rolled dough with melted butter, ensuring even coverage. Sprinkle generously with the cinnamon-nut mixture (about 4 tablespoons).

Cut the dough into a criss-cross pattern of 4 wedges, and slice each wedge into 4 triangles, totaling 16.

Starting from the wider end, roll each wedge into the shape of a crescent. Place on parchment-lined baking sheets, spaced 1 inch apart.

Preheat your oven to 350°F (175°C) and bake the cookies for approximately 22 to 25 minutes, or until golden brown.

Allow cookies to cool on the baking sheet for a few minutes before dusting them with powdered sugar.