Prepare the Eggs: In a small bowl, crack the two large eggs. Add the tablespoon of milk (if using), a pinch of salt, and a few grinds of black pepper. Whisk with a fork until the yolks and whites are just combined and the mixture is uniform. Be careful not to over-whisk; we want them combined, not frothy.

Sauté the Vegetables: Place a 20cm (8-inch) non-stick frying pan over a medium heat. Add the olive oil or butter. Once it's hot, add the sliced mushrooms and diced red pepper. Cook for 4-5 minutes, stirring occasionally, until they have softened and the mushrooms have released their moisture and started to brown slightly.

Wilt the Spinach: If you're using garlic, add it to the pan now and cook for 30 seconds until fragrant. Add the handful of spinach and stir for about 1-2 minutes until it has just wilted down. Remove all the vegetables from the pan and set them aside on a plate.

Heat the Pan for the Omelette: Wipe the pan clean with a piece of kitchen roll. Return it to a medium-low heat and add another small knob of butter if needed, swirling to coat the bottom of the pan. The pan is ready when the butter is melted and sizzling gently.

Cook the Eggs: Pour the whisked egg mixture into the pan. Let it sit for about 30-40 seconds until the edges just begin to set. Using a silicone spatula, gently push the cooked edges towards the centre, tilting the pan so the uncooked egg runs underneath. What works best for me is to continue this process around the pan for about 1-2 minutes.

Add the Fillings: Once the omelette is mostly set but still slightly moist on top, sprinkle the grated Cheddar over one half of the omelette. Spoon the cooked vegetable mixture over the cheese.

Fold and Serve: Cook for another minute until the cheese is gloriously melty. Carefully slide your spatula under the empty side of the omelette and fold it over the filling. Let it cook for another 30 seconds to ensure the centre is warm.

Plate and Garnish: Gently slide the finished cheese and veggie omelette from the pan onto a warm plate. Garnish with the freshly chopped chives and serve immediately.