Egg Eating can be a tough habit to break ( No Pun intended). There are several methods that can stop a hen eating her own eggs, but none are guaranteed 100% successful.
A Darkened Nestbox, with a curtain of sacking across the front may help. Hens only eat the egg they can see. At the same time provide plenty of loose Nesting material so the egg can sink into it out of sight of the Hen.
A 'roll-away' nest box, rather in the style of the old trap nests can work. These are boxes with sloping floors , so the freshly laid egg will roll to the back of the box, then drop through a gap at the back to a deeply littered floor beneath, out of reach of the hungry Hen.
Plenty of Dummy eggs, either Crock or Rubber ones can put a Hen off pecking at her eggs. Unsuccessful attempts at opening these artificial eggs can put less persistent birds off Egg eating, Discouraged by the lack off an eggy reward!
There are Plastic clip on Spectacle 'bits', that are commonly used by Gamekeepers/Game Farmers For Pheasant hens, to stop egg eating in Crowded laying pens. These act like Blinkers,and restrict the hen's forward vision so she can't see the egg to peck at it, yet she can still find food and water without a problem. If You are going to use 'specs', be careful to remove them from the hen's beak at the end of laying, as they can cause beaks to grow abnormally if left in for too long.
Personally I have never found the blown egg filled with mustard/Tobasco/Chili sauce to be effective, my hens seem to LOVE the taste of Hot n'Spicy things!
Any of these methods, either employed singly or combined may put a stop to your hen's bad habit. .or not! At the end of the day, if she remains a hardened offender, Culling maybe your only option.