Cream the softened unsalted butter with brown sugar and white sugar in a large mixing bowl using an electric mixer on medium speed for about 3-4 minutes until light and fluffy.

Add in one large egg, an extra egg yolk, and high-quality vanilla extract to the whipped butter mixture. Blend until smooth.

In a separate bowl, whisk together flour, baking soda, and sea salt. Gradually fold into the wet mixture until just combined.

Melt unsalted butter in a skillet and toast the kataifi until golden brown and crispy for about 5-7 minutes.

Mix the cooled kataifi with pistachio cream and form small balls. Freeze for about 30 minutes.

Preheat oven to 350°F (175°C). Flatten cookie dough, wrap around a filling ball, and roll into a smooth ball.

Bake the cookie balls in the preheated oven for 12-14 minutes or until edges are golden, and centers remain soft.

Remove cookies and let them cool on the baking sheet for about 5 minutes before transferring to a wire rack. Sprinkle with flaky sea salt.