Preheat the oven to 350ºF
Sift flour, baking powder, and baking soda into a large bowl. Stir in sugar.
In a separate bowl whisk together the eggs, olive oil and greek yogurt, until smooth.
Wash the plums and chop into pieces. You may use more or less plums if you desire.
Slowly stir the yogurt mixture into the dry ingredients in the large bowl, until just combined. Do not over stir this will make the muffins too dense. You want these plum muffins nice and moist.
Gently stir in the plums, with just a few turns.
Line the muffin pan with parchment paper and add about 2 tablespoons of plum muffin batter to the pan. Sprinkle the top with coarse sugar if you desire.
Bake the plum muffins for 18 - 20 minutes or golden brown.