Melt butter over low heat, then add minced garlic and shallots; toast until fragrant. Mix in mustard, lemon juice, lemon zest, cayenne, Calabrian chilies, smoked paprika, smoked salt, and black pepper, then stir to combine. Remove from heat and mix in chopped herbs.
Drizzle over steak, and enjoy!
Notes
Toasting the fresh garlic and shallot adds complexity to the flavor, but if you'd like to avoid using the stove altogether, you can simply mix all of the ingredients with softened butter.
You can enjoy this butter right off the stove like a sauce, or you can let it solidify in the fridge for a more spreadable texture.
When the butter is melted, it will separate. If you want a more consistent, creamy texture, you can simply mix the ingredients with room-temperature butter and skip the stove entirely.
For a beautiful presentation, you can pour the liquid butter into a butter mold before refrigerating. You can also roll room-temperature butter into a log using parchment paper.
Store in an airtight container in the refrigerator for up to 1 week. After that, freeze for up to 6 months.
You can reheat cowboy butter over low heat on the stove or in the microwave in 15-second bursts until it melts.