Prepare the streusel topping: In a mixing bowl, combine 1 cup of all-purpose flour, 1/2 cup of granulated sugar, and a pinch of salt. Pour in 1/4 cup of melted unsalted butter, mixing until you achieve a coarse crumb texture. Set aside.

Make the cream cheese filling: In a separate bowl, blend together 8 ounces of softened cream cheese, 1/4 cup of granulated sugar, 2 tablespoons of cornstarch, and 1 teaspoon of vanilla extract. Mix until smooth and creamy.

Combine dry ingredients: In a large bowl, whisk together 2 cups of all-purpose flour, 2 teaspoons of baking powder, and a pinch of salt. Set aside.

Mix wet ingredients: In another bowl, whisk together 1 large egg and 3/4 cup of light brown sugar until pale and fluffy. Add 1/2 cup of Greek yogurt, 1/4 cup of melted unsalted butter, and 1 teaspoon of vanilla extract. Stir until well combined.

Combine wet and dry mixtures: Gently fold the wet mixture into the dry ingredients using a spatula until just combined.

Add berries: Gently fold in 1 cup of mixed berries into the batter, keeping the berries whole.

Assemble muffins: Preheat your oven to 350°F (175°C) and line a muffin pan with paper liners. Portion about two-thirds of the batter into each muffin cup, creating a well for the cream cheese filling. Spoon in the cream cheese mixture and sprinkle the streusel topping.

Bake: Place the muffin pan in the preheated oven and bake for 30-35 minutes until golden brown and a toothpick comes out clean.

Cool muffins: Once baked, allow the muffins to cool in the pan for about 5-10 minutes before transferring them to a cooling rack.

Prepare glaze: Mix 1 cup of powdered sugar with 2-3 tablespoons of milk until you achieve a smooth consistency.

Drizzle glaze over muffins: Once the muffins are cooled, drizzle the prepared glaze over the tops.