Prepare the spinach and sausage filling: Squeeze the thawed frozen spinach in a clean tea towel until no more green liquid drips out — you want it as dry as possible to stop the omelet becoming watery. In a large non-stick frying pan over medium-high heat, add the olive oil. When the oil shimmers and ripples across the pan, add the turkey sausage meat, breaking it apart with a wooden spoon. Cook for 5-6 minutes until the meat is browned and releases a savoury, slightly nutty aroma. The sausage should look crumbly with crispy edges, not wet or grey.

Cook the aromatics: Reduce the heat to medium and add the diced onion to the pan with the sausage. Stir frequently for 3 minutes until the onion turns translucent and softens, releasing a sweet, mellow scent. Add the minced garlic and cook for another 30 seconds until fragrant — you'll smell it immediately, so don't walk away at this stage or it will burn and turn bitter.

Combine the filling: Add the squeezed-dry spinach to the pan, stirring it into the sausage mixture. Cook for 1-2 minutes, just until the spinach is heated through and any remaining moisture has evaporated. You should see no steam rising from the pan. Remove the pan from the heat and let the filling cool for 5 minutes while you prepare the eggs.

Whisk the eggs: Crack all 8 eggs into a large mixing bowl. Add the milk or water, salt, pepper, and smoked paprika if using. Whisk vigorously for 45 seconds until the mixture is a uniform pale yellow with tiny bubbles on the surface. The eggs should feel light and airy when you lift the whisk — this aeration is what gives your batch omelets a tender texture after reheating.

Cook the first omelet: Wipe out the pan you used for the filling and return it to medium heat. Add ½ tablespoon of butter and swirl until it melts, foams slightly, then subsides — this takes about 30 seconds. Pour in a quarter of the egg mixture (roughly 120ml) and tilt the pan so the egg covers the bottom evenly. Let it cook undisturbed for 1 minute. The edges will start to look set and slightly opaque, while the centre remains slightly wet and jiggly.

Add the filling and cheese: Spoon a quarter of the sausage-spinach mixture (about 75g) onto one half of the omelet. Sprinkle a quarter of the grated cheddar (25g) over the filling. Let the omelet cook for another 30-45 seconds. You'll see the cheese begin to melt and turn glossy, and the edges of the omelet will lift slightly from the pan. The bottom should be a light golden brown — lift a corner gently with a spatula to check.

Fold and finish: Using a wide spatula, carefully fold the empty half of the omelet over the filling. Press down gently with the spatula for 10 seconds to seal the edges. Cook for another 30 seconds, then slide the omelet onto a plate. The outside should be a warm golden colour, and when you cut into it, the cheese inside will be melted and stretchy. Repeat steps 5-7 with the remaining butter, egg mixture, filling, and cheese to make three more omelets.

Cool for batch storage: Let the omelets cool completely on a wire rack for 15-20 minutes before wrapping. If you wrap them while still warm, condensation will make the eggs soggy. The omelets should be at room temperature, with no visible steam rising from them, before you move to the storage step.