Preheat oven to 425 degrees. Combine the dry ingredients in a medium bowl - flour, baking powder, and salt.
On low-medium heat, melt butter in a small pot. Do not let the butter brown. If you do - that's ok - it'll just have a slightly nutty flavor which is delicious too.
In a large mixing bowl, combine sugar and butter.
Use an electric mixer and cream the butter and sugar until creamy... takes about 2-3 minutes.
Add the wet ingredients - milk, yogurt, vanilla extract, and egg.
Blend for a couple of minutes until all the ingredients are well-combined.
Add the flour mixture to the wet ingredients.
Mix until well incorporated, however do NOT over-mix.
This is how your batter should look.
Take fresh blueberries that have been rinsed and dried. Add a tbsp of flour and mix. This prevents the blueberries from sinking to the bottom of the muffin.
Add the floured blueberries to the batter and fold them in (do NOT mix, FOLD).
The muffin batter is ready.
Grease the cupcake/muffin pan with coconut oil, or use muffin liners. Using an ice-cream scoop, scoop the batter into a cupcake or muffin pan.
Into the oven at 425 degrees for 10 minutes.
After 10 minutes, lower the oven temperature to 375 degrees and bake the muffins for another 10 minutes at 375.
Perfectly golden brown and delicious muffins are ready!