Melt your butter first so it has some time to cool down a little bit.
Next mix the flour, baking powder, baking soda, and salt.
In a separate bowl beat the eggs and sugar until pale yellow.
To this bowl add the buttermilk, Greek yogurt, lemon zest and juice, and melted butter.
Add the flour and stir until just combined.
Let the batter rest for 30 minutes to allow the fresh milled flour to fully hydrate. During this time preheat the oven to 425℉.
After 30 minutes fold in the blueberries.
Scoop batter into muffin tins. If using large parchment liners you will get about 9 muffins, If you are using normal lines you can probably get 12. Sprinkle with coarse sugar if desired.
Bake the muffins for 5 minutes, then lower the temperature of the oven to 350℉ (but don't open the oven door) and bake for 20-25 more minutes.
Remove from oven and place muffins on a wire rack to finish cooling. These muffins will stay fresh 3-4 days if stored in an airtight container on the counter.