Heat 2 tablespoons butter in a cast iron skillet over medium heat until melted. Add the sourdough bread slices to the butter and pan-fry the bread until it soaks up the bread and begins to color, about 2 minutes per side.
In a small mixing bowl, mix the anchovies, garlic, parmesan cheese and oregano together.
Spread the anchovy mixture on the grilled bread, and then transfer to the oven. Broil until warmed through and colored on the top, about 4 minutes. Serve warm with a light salad.