How to Make the Fluffiest Florentine Omelette

In a medium bowl, season eggs with salt and pepper, then whisk until homogeneous and frothy. Set aside. Add cheese to a separate medium heatproof bowl, and line a large plate with a double layer of paper towels. In a 10-inch nonstick skillet, melt 1 tablespoon (15g) butter over medium-high heat. Add garlic and cook, stirring frequently, until garlic is aromatic and just begins to soften, about 30 seconds. If using fresh spinach: Add spinach to skillet, cover, and cook until just wilted, about 2 minutes (you may have to press down on the spinach with the lid at first to cover, but the spinach will rapidly lose volume as it wilts). Uncover, season with salt and pepper, and stir to combine. Increase heat to medium-high and cook, stirring frequently, until spinach is very soft and most of the liquid it has released has evaporated, about 4 minutes. If using defrosted frozen spinach: Add spinach to skillet, season with salt and pepper, and stir well to combine. Increase heat to medium-high and cook, uncovered, until excess water has evaporated, about 4 minutes. Transfer cooked spinach to paper towel-lined plate, roll up in the towels, and squeeze gently to extract any additional excess moisture; discard paper towels and any accumulated liquid. Transfer hot spinach to bowl with cheese. Wipe out now-empty skillet, and melt remaining 1 tablespoon (15g) butter over medium heat, swirling frequently, until butter is lightly browned. Re-whisk eggs until foamy, then add to skillet and cook, using a silicone spatula to push the edges in toward the center as they set and tilting the pan to spread the uncooked egg underneath. Continue pushing in the edges of the eggs and tilting the skillet, working all around the pan, until omelette is almost set, about 45 seconds. Sprinkle spinach and cheese mixture over half of omelette, remove from heat, cover, and let omelette sit until mostly or fully cooked through on top (depending on your preferred consistency), about 1 minute. Using silicone spatula, loosen the edges of the omelette from skillet and shake skillet to ensure that it's not stuck. Carefully fold omelette in half to enclose the filling, then slide it onto a serving plate and serve immediately.