Preheat oven to 350 degrees, with the rack in the middle position.
In a large mixing bowl, whisk together flour, baking powder and salt. Add in blueberries and toss to combine.
In a separate medium mixing bowl, whisk egg for about 20 seconds until it becomes lighter in color and slightly frothy. Add sugar to the egg and whisk to combine. Then add in butter and whisk to combine. Add greek yogurt in 2 steps, whisking until just combined.
Pour the wet ingredients into the dry ingredients, and gently fold until just combined. The batter should look a little dry and stiff, and there may still be a few pockets of dried flour.
Spray a 12 muffin tin with non-stick cooking spray. Divide the batter evenly, and bake for 25-30 minutes until golden brown and an inserted skewer comes out clean. Rotate the muffin tin halfway thru baking.
Allow to cool for 1 minute, then invert the mufins on a wire rack to cool for a few more minutes.
Eat warm, or keep an an airtight container for up to 1 week.