Gently rinse and dry the blueberries, then place them in a Dutch oven. Sprinkle in the sugar, water, and ground cinnamon (if desired) and stir well.

Turn heat to medium-high and bring the mixture to a low simmer for about 5-10 minutes.

In a mixing bowl, sift together the flour, baking powder, and salt. Cut in the cubed butter until the mixture resembles coarse crumbs.

Gradually add in the cold milk to the dry ingredients, mixing gently until a soft, sticky dough forms.

Drop heaping tablespoons of the dumpling dough over the simmering fruit mixture.

Cover the pot tightly with a lid and reduce heat to low. Let the dumplings steam for 15 minutes without lifting the lid.

After 15 minutes, check the dumplings for doneness; they should be puffed up and cooked through.

Spoon portions of the Blueberry Grunt into bowls and serve warm, optionally with vanilla ice cream or whipped cream.