Prepare the streusel by combining ½ cup of all-purpose flour, ¼ cup of light brown sugar, and a pinch of salt. Mix in ¼ cup of melted butter until coarse crumbs form, then set aside.

Make the cream cheese filling by blending 8 oz of softened cream cheese, ¼ cup of granulated sugar, 1 tablespoon of cornstarch, and 1 teaspoon of vanilla extract until smooth.

Prepare the muffin base by whisking together 1 ½ cups of all-purpose flour, 2 teaspoons of baking powder, and ½ teaspoon of salt. In a separate bowl, beat 1 egg and ½ cup of granulated sugar until fluffy. Add ½ cup of Greek yogurt, ⅓ cup of vegetable oil, and 1 teaspoon of vanilla extract. Gradually combine wet and dry ingredients, folding in half of the mixed berries.

Preheat the oven to 350°F and line a muffin tin with paper liners. Spoon 1½ tablespoons of batter into each cup, making a dent for the cream cheese filling. Add 1 tablespoon of filling and top with more batter. Sprinkle streusel on top.

Bake for 30-35 minutes until golden and a toothpick comes out clean.

Cool in the pan for 5-10 minutes before transferring to a wire rack to cool completely.

For optional glaze, mix 1 cup of powdered sugar with 2-3 tablespoons of milk until desired consistency. Drizzle over cooled muffins.