In a mixing bowl, cream together 1/2 cup of softened butter and 3/4 cup of granulated sugar until fluffy and light in color, about 2-3 minutes. Then, add 1 egg yolk and 1 teaspoon of vanilla extract, mixing well.

Gradually sift in 1 cup of plain panko breadcrumbs along with a pinch of salt, mixing gently using a spatula or mixer on low speed until a soft dough forms.

Using a tablespoon, scoop out portions of dough and roll them into balls, about 1 inch in diameter. Roll each ball in additional panko breadcrumbs until coated.

Preheat the oven to 350°F (175°C). Place the baking sheet with cookie dough balls inside and bake for approximately 15 minutes, or until golden brown around the edges.

After baking, allow the cookies to cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely.