Add the blueberries, water, sugar, and 2 tablespoons of butter to a medium-large pot with a tight-fitting lid. Bring to a boil over medium-high heat, then reduce the heat and simmer 1–2 minutes until the berries are juicy and loose, not syrupy.

Meanwhile, in a mixing bowl whisk together the flour, baking powder, sugar, and salt.

Rub the ⅓ cup of room-temperature butter into the flour mixture with your fingertips until it resembles coarse crumbs.

Make a well in the centre and pour in the milk. Stir gently with a fork until a soft, shaggy dough forms.

Use a spoon to drop portions of the dumpling dough evenly over the surface of the hot berries, leaving space between pieces for steam circulation.

Cover the pot tightly with a large square of parchment paper and then the lid. Reduce heat to low so the berries bubble softly and steam the dumplings for about 15 minutes.

Remove the lid and carefully lift off the parchment paper. Serve the blueberry grunt warm, with vanilla custard, ice cream, or whipped cream if desired.