In a saucepan over medium heat, melt the butter and cook until it turns a deep golden brown and has a nutty aroma. Transfer to a bowl and let it cool slightly.

In a mixing bowl, whisk together the slightly cooled brown butter and powdered sugar until smooth.

Stir in the vanilla extract until well combined.

Gradually add the flour and salt, mixing until just combined. If using, fold in the chopped almonds.

Turn the dough onto a floured surface, shape it into a log about 1.5 inches in diameter, and wrap it tightly in plastic wrap. Chill in the refrigerator for at least one hour, or until firm.

Preheat your oven to 350°F (175°C). Unwrap the chilled dough and slice it into 1/4-inch rounds, placing them about 2 inches apart on parchment-lined baking sheets.

Bake in the preheated oven for about 12-15 minutes or until the edges are just starting to turn golden.

Allow the cookies to cool on the baking sheet for a few minutes before transferring them to a wire rack.