How to make
In a bowl, beat the eggs and sugar with a mixer, until a homogeneous mixture is obtained. Pour the oil in a thin stream, then add the vanilla.
In a separate bowl, mix the flour, cinnamon, nutmeg, salt and baking soda.
Using a wooden spoon, mix the flour mixture with the wet mixture and sour cream (or thick yogurt).
Add the diced apple and mix again with the spoon. Divide the sponge cake mixture into the paper muffin cups.
For the topping, mix the flour, brown sugar, cinnamon, salt and cold butter (cut into pieces) in a bowl. Using your hands, mix all the ingredients until they become crumbly.
Spread the prepared topping evenly over the muffins, by pressing it lightly into the batter.
The apple muffins are baked for about 25 minutes, or until when you check them with a toothpick in the center, it comes out out clean.
When they are ready, take them out of the oven and leave them to cool for about 10-15 minutes. Then carefully remove them from the muffin tin to cool completely on a wire rack.
The apple muffins with topping are ready.
