Hi Sandra
Great you have hedgehogs visiting, I aim to put enough food out that there’s always a little left the next morning & as you say hogs are coming to an empty dish then I suggest you put more out. Some nights you’ll get more sometimes less visits as they cover a wide area each night & don’t include your garden every time so you may even find nothing’s been eaten occasionally but that’s wildlife for you, unpredictable.
I hope you also put a shallow dish of clean water out as that’s equally important to hedgehogs & very importantly NO mealworms as these cause metabolic bone disease & the hedgehogs die a lingering & very painful death.
Good luck hedgehog watching.