For the butter:

1/2 cup (1 stick) unsalted butter, softened to room temperature

1 tin Fishwife anchovies, finely chopped

3-4 sprigs fresh rosemary, finely chopped

2 large garlic cloves, grated

1 lemon, zested

1 teaspoon red pepper flakes

Freshly ground black pepper

For the steak:

1 (1 1/2-inch) thick bone-in ribeye

Kosher salt, to taste

Freshly ground black pepper, to taste

Vegetable oil, for searing

Let the steak sit at room temperature for at least 1 hour. Pat steak dry with a paper towel. Salt and pepper generously all over.

Make the butter. In a medium bowl, mix all the ingredients until fully combined. Transfer to a tupperware or plastic wrap and keep refrigerated. Butter will keep up to 1 month.

Make the steak. Preheat a large cast iron over medium high heat. Add 1-2 tablespoons vegetable oil. Once barely smoking, add steak and cook undisturbed until golden brown, 3-4 minutes. Use tongs to flip to other side and cook until browned. For medium rare, cook to an internal temperature about 135F. Remove from heat and add a generous spoonful anchovy butter. Tilt the pan and use a spoon to baste the butter on top of the steak several times. Flip the steak and repeat.

Let steak cool on a cooling rack for 5 minutes. Slice and serve immediately with more anchovy butter.