In a medium bowl beat the cream cheese with an electric mixer until fluffy. Add the butter and mix until blended.
Add the sugar to the cream cheese mixture and mix until incorporated. Mix in the eggs.
Add the lemon zest and mix in. Mix in the lemon juice and milk.
Sift together the flour, baking, soda, baking powder, and salt. Add to the wet ingredients and on the low speed of the mixer, mix in just until the flour is mixed in.
Gently fold in the blueberries.
Fill the muffin tins so that they are about 3/4 of the way full. Place in the preheated oven and bake 16 to 18 minute. The edges should be lightly browned.
Remove from the oven and cool completely.
While the muffins are cooling mix together the icing.
In a small bowl add the powdered sugar gradually add the lemon juice until the right consistency. Beat with a spoon until the icing is smooth. Drizzle the icing over the muffins.
These are best eaten fresh. They can be frozen, but I would add the icing after they are taken out of the freezer and defrosted.