Move rack to middle position in oven. Heat oven to 400 degrees F. Spray
a muffin pan with PAM.
In a large bowl, whisk together flour, baking powder and salt. Set aside.
In a medium bowl, combine water and cornstarch. Whisk until blended. Whisk
in milk, brown sugar and vanilla extract. Whisk in the butter and immediately
pour liquid into the dry mixture, along with the blueberries.
Using a wooden spoon, stir batter so that it is just blended - do not over-mix.
Pour batter evenly into muffin tins.
Mix together sugar and cinnamon and gently
sprinkle over each muffin.
Bake for 13-15 minutes, using a wooden pick to check doneness.
Let cool for 2 minutes.
Run a sharp knife around edge of each muffin to loosen from pan.
Gently lift out onto a plate and serve warm.