Preheat the oven to 180°C (Gas Mark 4 / 350°F).
Peel the apples, and cut into small chunks.
Add the eggs, goat's yogurt, oil, honey, and vanilla to a large jug, and mix well to combine. Add the chopped apples, and mix again.
In a separate mixing bowl, combine the wholemeal flour, oats, baking powder, cinnamon, and nutmeg.
Pour the wet ingredients into the dry, and mix thoroughly.
Place some muffin cases into a muffin tray (I like to use silicone cases so there's no sticking) - you should be able to make around 10 muffins in total. Divide the mixture between the cases, filling each around ¾ of the way to the top.
Sprinkle each muffin with a few extra oats, and bake for around 25-30 minutes. The muffins should be lightly browned on top, and a skewer should come out clean.
If using silicone cases, allow the muffins to cool for a few minutes (or a bit longer!), then carefully remove them from the cases, and finish cooling on a rack. If using paper cases, just transfer the muffins to the rack when they're cool enough to handle.