Preheat your oven to 375°F (190°C) and line a muffin tin with paper liners.

Toss the blueberries in 1½ tablespoons of flour to prevent sinking.

Whisk together the flour, cornstarch, baking powder, cinnamon, and salt in a medium bowl.

In a large bowl, mix the oil, melted butter, and sugar until blended, then add eggs, milk, and vanilla.

Stir the dry ingredients into the wet mixture until just combined and fold in the blueberries.

Mix cream cheese, sugar, egg yolk, and vanilla in a separate bowl until creamy.

In another bowl, mix flour, brown sugar, cold butter, and salt to form streusel.

Fill muffin liners two-thirds full with batter, add cream cheese filling, and top with streusel.

Bake for 25 minutes or until a toothpick comes out clean.

Cool in the tin for 15 minutes before transferring to a wire rack.