Begin by blending 1½ cups of fresh or thawed blueberries in a food processor until you achieve a smooth puree. This only takes about 1-2 minutes.

Pour the blueberry puree into a medium saucepan and cook it over medium-low heat for about 10-12 minutes, until it reduces to about ½ cup.

Preheat your oven to 325°F (163°C). Line an 8x8 inch glass baking dish with parchment paper.

In a large mixing bowl, combine 10 tablespoons of melted unsalted butter with 1¼ cups of granulated sugar and whisk until slightly frothy before adding the eggs, vanilla extract, and sea salt.

Gently fold in the cooled blueberry puree into the wet mixture.

Slowly sift in 1 cup of all-purpose flour, stirring gently with a spatula until just combined.

Spread the brownie batter evenly in the prepared baking dish and bake for 35-40 minutes.

Once baked, remove the brownies from the oven and let them cool completely.

In a medium mixing bowl, whisk together 1 cup of sifted powdered sugar, 2 tablespoons of milk, and ⅛ teaspoon of vanilla extract until smooth.

Spread half of the glaze over the cooled brownies and let it set for about 10 minutes before adding the remaining glaze.

Cut the brownies into 16 squares while still in the dish and transfer them to an airtight container.