1. Heat a sauté pan over medium high-heat until water sizzles upon contact.
2. Place 1 tablespoon Plugrá Butter in the pan and shake the pan gently while the butter melts to maintain emulsification.
3. When the butter is melted, add the shallots and a pinch of salt.
4. Stir until shallots are translucent. Then increase the heat to high and pour in the apple cider and brown sugar.
5. Jiggle the pan lightly and stir the sugar into the cider while the cider reduces.
6. Allow cider to reduce to a few tablespoons, and then add the heavy cream. Stir and then remove from heat and place on a heat-proof surface.
7. Add the Plugrá Butter cubes one at a time, whisking as you go. Maintain a consistent temperature.
8. Continue adding butter until the sauce coats the back of a spoon without running.