Whisk sugar and egg.
Add sour cream.
Add dry ingredients.
Add some blueberries. Reserve some for top.
Spoon some batter into bottom of 6 prepared muffin cups.
Dollop on cream cheese and top with more batter.
Top with reserved berries and streusel.
Pace them in the oven and bake at 400 degree for 5 minutes, then lower temp to 375 and bake 15 mins more.