- 1 tablespoon unsalted butter
- 1 teaspoon diced shallot
- 1 tablespoon diced red onion
- 1 clove garlic, finely diced
- 5 baby portobello mushrooms, sliced – or more to taste
- 1/2 (12 fluid ounce) bottle lager beer (such as Sam Adams® Winter)
- 3 sprigs fresh rosemary
- 1 pinch Cajun seasoning
- 1 tablespoon honey
- Melt unsalted butter in a skillet over medium heat. Add shallot, red onion, garlic, and mushrooms; cook and stir until mushrooms begin to give up their liquid, about 10 minutes.
- Pour beer into skillet; simmer until liquid is reduced by half, about 10 minutes. Add rosemary sprigs and stir in Cajun seasoning. Simmer another 5 minutes. Stir in honey. Turn heat off and allow sauce to cool slightly before using.