Preheat the oven to 425°F. Take muffin size bake tin and grease it using ghee or butter. Line up cake liners and set them aside. (You can take a muffin tin that can hold 10 muffins).
Take a medium-sized mixing bowl. In the bowl, combine all the ingredients mentioned under streusel. Mix the ingredients well using a pastry cutter, fork, or spatula until it takes a wet sand structure.
Take a large mixing bowl. Add melted butter and granulated sugar. Beat until well combined. Once done, add eggs, buttermilk, vanilla extract, and greek yogurt. Combine all the ingredients until it turns into a smooth form. Into the bowl, add baking powder, flour (2 cups), and salt. Mix them completely until its fully incorporated. Toss the blueberries into the flour (two Tablespoons). Once done, fold the tossed blueberries into the batter and mix it well.
Using a scooper, scoop the batter and place it into the greased muffin tin. You can use the scoop size based on the size of your muffin tin. (Care to fill only 3/4 of the muffin tin).
Sprinkle 2 tablespoons of prepared streusel mixture on the top of each scooped muffin arrayed in the muffin tray. Press the streusel gently to make sure that it sticks to the batter.
Keep the batter-filled muffin tin in the preheated oven and bake for 5 minutes at 425°F. After 5 minutes, turn down the oven temperature to 375°F and bake for 15 minutes. If baked muffins are found to be in golden brown color, it's perfectly baked!
Remove the tin from the oven and allow it to cool. Once the muffins reached room temperature, you can detach them from the tray.
Your soft, healthy Blueberry Streusel Muffins are now ready to serve.