Preheat the oven to 325°F (165°C). Lower than a standard bake — this matters for texture.
Blend the eggs and cottage cheese together for 30 to 45 seconds, until completely smooth with no visible curds.
Fold in the Gruyère, spinach, spring onion, salt and pepper by hand.
Grease a 12-cup muffin tin thoroughly, including up the sides — this is not optional.
Divide the mixture evenly among the cups, filling each about ¾ full.
Set the muffin tin inside a larger roasting pan and pour hot water into the roasting pan until it reaches halfway up the muffin cups.
Bake 25 to 30 minutes, until the bites are set but still slightly soft in the centre.
Cool in the tin 10 minutes before removing.