Preheat the oven to 220℃. Season the steak and leave to stand at room temperature for 30 minutes.

Heat a cast iron skillet pan over a medium-high heat. Add 1 tbsp of cooking oil, add the steak to the pan and cook for 3-4 minutes until completely browned on one side.

Turn it over and cook for a further 2 minutes. Then add the butter, 3 crushed garlic cloves and two sprogs of rosemary. Carry on cooking until the steak is browned all over.

Transfer the steak to an oven tray, and place into the oven for about 10 minutes, or until done to your liking.

Meanwhile, fry the mushrooms in the skillet pan for 2-3 minutes, while that is cooking finely chop the remaining rosemary and slice the garlic.

Add the garlic and rosemary into the pan and fry for a further 2 minutes.

Pour in the white wine and reduce by half. Add the spinach, and cook until it has wilted.

Now add the dijon mustard and the creme fraiche, mix well. Turn down the heat.

Take the steak out from the oven and place on a chopping board, cover it in tin foil and leave to rest for 5 minutes before slicing into thick slices.

Serve the steak slices over the creamy mushrooms and spinach.