Start by preheating the oven to 425 degrees F. Line a muffin tin with paper liners or grease the muffin tin.
Next, make the cream cheese filling by adding cream cheese, white sugar, and vanilla to a stand mixer (or bowl) and beating it all together. Set aside.
In another bowl, make the streusel by combining the flour, brown sugar, white sugar, and cinnamon. Stir in the melted butter until you get a "crumbly-looking" texture. Set aside.
Next, make the muffin batter by whisking together the flour, baking powder, and salt in a large bowl. Then, in another bowl, whisk together the melted butter, white sugar, eggs, vanilla, and milk.
Pour the wet ingredients into the dry ingredients and stir until just combined. Don't overmix. Fold in the blueberries.
Assemble the muffins by filling each muffin liner a little over halfway with batter. Add about a spoonful of cream cheese filling to the top. Optional, add a few extra blueberries to the tops of the muffins. Then generously sprinkle on the streusel topping over each muffin.
Bake at 425 degrees F for 5 minutes. Then, without opening the oven, reduce the oven temp to 350 degrees F and continue baking for about 14-18 minutes. You will know that the muffins are done because the streusel will look darker and the muffins will have a golden-brown tint to them when looked at from the bottom.
Let them cool either in the muffin tin or on a wire rack and enjoy! :)