Melt the butter in a saucepan over medium heat until it turns golden brown and smells nutty. Whisk frequently and watch closely, as the butter browns quickly. Let it cool to room temperature.

Add the browned butter with the vanilla extract, regular sugar, salt, and cinnamon to a mixing bowl, and beat until frothy.

Add the flour and knead into a smooth dough. The dough may be slightly crumbly—that’s normal for German shortbread cookies.

Roll the dough into logs, about 1.2 inches (3 cm) in diameter, and wrap them tightly in plastic wrap. Smaller logs will make smaller cookies.

Refrigerate the Heidesand dough logs for at least 2 hours or until firm.

Let the logs soften slightly at room temperature, then cut them into ¼-inch (0.5 cm) thick slices. Place the slices on a baking tray lined with parchment paper. Bake at 350°F (180°C) for about 12 minutes. The cookies should remain light in color. Let the German shortbread cookies cool completely.