Muffins:

1. Preheat your oven to 180 ºC and spray a muffin pan with some non-stick spray.
2. In a blender, add the oil and sugar, and blend well for a minute. Add the mandarins (quartered and seeded), and keep blending until you get a smooth batter, and there are no chunks of fruit. Add the eggs and vanilla essence. Keep blending for 2 more minutes.
3. Pour the mix into a big bowl and using a spatula, fold in the flour and salt.
4. Using an ice cream scoop or a regular spoon, pour the mix into the muffin pan, filling them up about 3/4.
5. Bake for 18-20 minutes, until they are golden brown. If you insert a toothpick in the middle and it comes out clean, remove them from the oven.
6. Let them cool completely before covering them with the chocolate ganache.

Dark Chocolate Ganache (optional):

1. In a mid-size saucepan, heat the cream at medium heat until it simmers.
2. Once it simmers, pour over the chocolate in the medium bowl, without stirring. Let it rest for a few minutes.
3. After a few minutes, using a fork or spoon, mix until you get an even consistency.
4. Let it rest to room temperature.
5. Pour the desired quantity over the muffins.