Preheat oven to 400 degrees F. Coat a 12-cup muffin pan with non-stick cooking spray.
In large bowl beat eggs with an electric hand mixer. Add 1 cup white sugar and beat for a minute or two until completely combined. Pour in the oil, with beaters running, and then add vanilla. In a separate bowl, stir together flour, 1/2 cup granola (reserve the rest for topping), salt and baking soda.
Using a wooden spoon, mix dry mixture into wet mixture a little at a time, alternating with the Greek yogurt.
Add the blueberries and mix with the wooden spoon just until combined. Divide the batter between the prepared muffin cups. Sprinkle muffin tops with remaining granola.
Bake in preheated oven for 18 to 20 minutes, or until muffins are cooked through and granola topping is golden brown. Watch closely towards end of baking time and if granola is browning too quickly, lightly lay a sheet of foil over the top for remaining baking time.
Remove from oven and allow muffins to cool for about 10 or 15 minutes and then carefully remove from tin to cool completely. Store leftovers in an airtight container.
Granola topping will be have a crunchy, slightly chewy texture when muffins are fresh and will soften a bit more if stored for more than 24 hours.