In a large mixing bowl, whisk together all-purpose flour, granulated sugar, instant yeast, and kosher salt.

In a saucepan, heat unsalted butter, warm water, whole milk, and vanilla extract until warm but not hot.

Combine the wet ingredients with the dry ingredients, stirring until a dough forms, then knead for about 8-10 minutes until smooth.

Place the kneaded dough in a greased bowl, cover with a towel, and let rise for about 30-45 minutes until doubled in size.

After the first rise, gently punch down the dough, wrap tightly in plastic wrap, and refrigerate for at least 1 hour.

Preheat your oven to 400°F. Toss fresh blueberries with unsalted butter and lemon zest until coated, then roast for 10-15 minutes.

Once the dough is chilled, roll it into a large rectangle, spread roasted blueberries, cut into strips, and stack them in a greased loaf pan.

Cover the loaf pan with a towel and allow it to rise for another 45-60 minutes until it has doubled in size again.

Preheat your oven to 350°F. Bake for 35-40 minutes, covering loosely with foil halfway through to prevent over-browning.

Remove from the oven, let cool in the pan for about 10 minutes, prepare glaze, drizzle over the warm loaf, and serve.