In a small bowl, combine all-purpose flour, light brown sugar, and salt. Pour in melted unsalted butter and mix until the mixture resembles coarse crumbs. Set aside.

In a mixing bowl, blend room temperature cream cheese, granulated sugar, and cornstarch until smooth and creamy. Incorporate the vanilla extract.

In a large mixing bowl, whisk together the dry ingredients: all-purpose flour, baking powder, and salt until well combined. In a separate bowl, combine the egg, granulated sugar, Greek yogurt, and melted butter, whisking until smooth. Gently fold these wet ingredients into the dry mixture.

Carefully incorporate the wet ingredients into the dry mixture using a silicone spatula until just combined. Fold in half of your fresh mixed berries.

Preheat your oven to 350°F and prepare a muffin tin by lining it with paper liners or greasing it lightly. Spoon the muffin batter into each cup, filling them about two-thirds full, creating a small dent in the center of each filled cup.

Spoon a generous dollop of your prepared cream cheese filling into the center of each muffin cup, topping each with the remaining mixed berries.

Sprinkle the reserved streusel topping generously over each muffin, pressing it down lightly.

Place the muffin tin in the preheated oven and bake for 30–35 minutes, until the tops are golden brown and a toothpick comes out clean.

Once baked, remove the muffins from the oven and allow them to cool in the pan for about 10 minutes. Transfer to a wire rack to cool completely.

Prepare a simple glaze by mixing powdered sugar with a splash of milk until you reach the desired consistency. Drizzle over the cooled muffins.

Enjoy warm or at room temperature!