Prepare the Streusel Topping: In a small bowl, mix the flour, brown sugar, and salt. Drizzle the melted butter over the mixture and mix until it achieves a crumbly consistency. Set aside.

Make the Cream Cheese Filling: In another bowl, mix together the softened cream cheese, granulated sugar, vanilla extract, and cornstarch until smooth. Set aside.

Prepare the Muffin Batter: Preheat your oven to 350°F (175°C). Prepare a muffin tin by placing paper liners in each cup or by greasing it with butter. In a medium-sized bowl, combine the flour, salt, and baking powder, then whisk until well blended. In a separate large bowl, combine the vegetable oil, granulated sugar, egg, vanilla extract, and Greek yogurt. Whisk until smooth.

Carefully incorporate the dry ingredients into the wet mixture, mixing until they are barely combined. Do not overmix. Toss half of the blueberries with 1 tablespoon of flour and fold them into the batter.

Assemble the Muffins: Spoon the muffin batter into each liner until they are filled to about halfway. Spoon about 1 teaspoon of the cream cheese filling into the center of each muffin. Add more batter on top until each muffin cup is about ¾ full.

Sprinkle the remaining blueberries over the top, then add a generous amount of the prepared streusel topping.

Bake the Muffins: Place in the preheated oven and bake for 22 to 25 minutes, or until a toothpick inserted into the center comes out clean (note that the cream cheese may leave it a bit moist). Allow the muffins to cool in the pan for 5 minutes before moving them to a wire rack to cool completely.

Add the Glaze: Once the muffins are cool, mix the powdered sugar with 1 ½ to 2 ½ teaspoons of milk or cream to create a smooth glaze.