Preheat oven to 400 degrees. Grease jumbo sized or standard size muffin tins and line with parchment paper or cupcake liners. Set aside.
In a mixing bowl combine the ingredients for the streusel using a fork or your hands. The topping will be a crumbly pea like texture, similar to biscuit dough before kneading.
In a large bowl combine sugar, and melted butter and mix until combined. Add the eggs, greek yogurt, buttermilk, vanilla, and lemon juice.
Add the dry ingredients to the wet. Flour, baking powder and salt. Mix until just combined.
In a bowl add blueberries and toss with 1-2 tbsp of flour to coat the berries. This will keep them from sinking. Fold the blueberries into the batter, mixing until just combined.
With a large ice cream or cookie scoop, scoop the batter into the prepped muffin tins filling them 3/4 of the way.
Sprinkle the muffins with the streusel topping.
Bake for 25-30 minutes , until muffins are golden and a knife comes out just clean.
Remove from the oven and allow to cool before eating. Enjoy!