Preheat oven to 400 degrees
In a large mixing bowl, whisk together the eggs & sugar until combined.
Whisk in the yogurt, oil & vanilla extract.
Fold in the flour, baking powder & salt.
In a small bowl - combine 1½ cups blueberries & 1 tbsp flour & toss to coat.
Fold the flour-coated blueberries into the batter.
Spoon the batter into the muffin pan, filling each well about ⅔ full. (lined or sprayed with cooking spray if not using the flexipan)
Add a small spoonful of the blueberry drizzle over the top of each well full of batter.
Sprinkle with the remaining fresh blueberries.
Top with the streusel - sprinkling generously with the topping.
Place in the oven & then REDUCE HEAT TO 375 degrees.
Bake 18-22 minutes or until toothpick test is clean.
Cool for 5 minutes in the pan before transferring to a wire rack to continue cooling - or serve warm.