Heat a large non-stick or cast iron pan over a medium-high heat and add the butter, ghee or olive oil.
Once it has melted add the garlic, mushrooms, thyme and a good pinch of sea salt and black pepper. Stir well so that the mushrooms are coated in the butter.
Cook for 3-4 minutes stirring occasionally, until the mushrooms soften and brown.
Add the vinegar and spinach and stir for 30 seconds to just wilt the spinach. Set aside.
Crack the eggs into a mixing bowl, season with a pinch of sea salt and black pepper, then beat well with a fork until fully combined.
Add a little more butter to the hot pan, then carefully pour in the eggs.
Tilt the pan so that the egg thinly coats the base of the pan.
Grate the cheese onto a board and sprinkle over the egg.
Now add the mushrooms to the centre of the omelette wrap and fold in the edges to form a parcel.