Prepare the Streusel Topping: In a medium bowl, combine 1/4 cup of all-purpose flour, 1/4 cup of granulated sugar, and a pinch of salt. Mix before adding 2 tablespoons of melted unsalted butter. Stir until crumbly and set aside.

Make the Cream Cheese Filling: Beat together 8 ounces of softened cream cheese, 1/4 cup of powdered sugar, 2 tablespoons of cornstarch, and 1 teaspoon of vanilla extract until smooth.

Combine Dry Ingredients: In a large bowl, whisk together 2 cups of all-purpose flour, 2 teaspoons of baking powder, and 1/2 teaspoon of salt.

Whisk Wet Ingredients: In another bowl, crack one egg and whisk it with 3/4 cup of granulated sugar until pale yellow. Fold in 1 cup of Greek yogurt, 1/4 cup of vegetable oil, and 1 teaspoon of vanilla extract.

Combine Mixtures: Fold the wet and dry mixtures together until just combined, then stir in 1/2 cup of blueberries and 1/2 cup of raspberries.

Assemble Muffins: Preheat the oven to 375°F (190°C). Spoon batter into a muffin tin, create a well in the center, add cream cheese filling, sprinkle berries, and top with streusel.

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

Cool and Glaze: Cool in the pan for 10 minutes, then drizzle with a glaze made from 1/2 cup of powdered sugar and 1-2 tablespoons of milk.