For the Muffin Tops

1. Preheat oven to 350 degrees.  Line a baking sheet with parchment paper and set aside.
2. Measure out 1/2 cup of heavy cream plus 1/2 cup of milk together, and place in the freezer to chill for 5-10 minutes.
3. In the meantime, mix all-purpose flour, sugar, baking powder, and salt into a medium bowl and whisk together.
4. Melt butter and pour into the chilled milk and cream.  
5. Add cream mixture to flour mixture, along with the lemon zest, lemon juice, and vanilla extract.  Stir until just combined.  
6. Gently fold in blueberries.
7. Scoop batter onto the baking sheet.  I use a spring-loaded ice cream scoop to drop about 2 heaping tablespoons of batter per muffin top, 12 per baking sheet.  
8. Bake at 350 degrees for 12-15 minutes.  Transfer to a cooling rack, and then drizzle the glaze over each cooled muffin top.  The glaze will harden as it cools.

For the Glaze

1. In a small bowl, whisk together powdered sugar, lemon juice, heavy cream and salt.  Add water by the 1/2 teaspoonful, whisking as you go, until the glaze is a drizzling consistency.