Fresh Blueberry Brioche

Place fresh blueberries on a plate and freeze in a single layer. (Do not use frozen blueberries, as they are too watery.)
Slightly warm milk and pour into bowl of a stand mixer fitted with dough hook attachment. Add yeast and whisk by hand to combine. Add all-purpose flour, bread flour, 2 1/2 tbsp sugar, salt, eggs, and egg yolk to bowl. Mix on low speed until dough comes together, 1-2 minutes.
Increase mixer speed to medium-low and work dough for 6 minutes. Pause every minute to push dough back down and off the hook until it pulls off the bowl sides and looks like a strong bread dough.
Reduce mixer speed to low and slowly add butter, a little at a time, over the course of 2 minutes (pausing after 1 minute to scrape down bowl and hook). When butter begins to blend in, increase mixer speed to medium-high to fully incorporate butter and bring the dough back together, 5-6 minutes longer.
Place dough on a lightly floured work surface and press into a 16" x 10" rectangle with a short side nearest you; distribute blueberries and 2 tbsp sugar along the top edge and gently roll down, toward you, into a log.
Place on a greased baking sheet, wrap in plastic, and refrigerate for at least 1 hour, or preferably overnight.
Grease a 9" x 5" loaf pan. Reshape dough by pressing it into a 12" x 6" rectangle with a short side nearest you. Sprinkle with remaining 2 tbsp sugar and tightly roll down toward you.
Place into greased loaf pan, loosely wrap in plastic, and allow to rise in a warm place until more than doubled in size, about 3 hours.
Preheat oven to 350°. Carefully brush dough with Egg Wash, making sure egg doesn't pool around the edges. Liberally sprinkle with sugar. Bake until golden, 40-45 minutes. Allow to cool for about 15 minutes in the pan. Then transfer to a cooling rack.