Notes: I've been intrigued by the use of what Milk Bar calls “MSG for bakers”, i.e. milk powder. Our pantry has a bag of it because some of the bread recipes I make call for it. It's used in this cookie recipe to make "milk crumbs": basically, a streusel topping enhanced with milk powder and white chocolate. Since the basic recipe makes twice the quantity required for the blueberry cookies, I made two batches this week.
I'm surprised Tosi is surprised about the existence of dried blueberries. Even though the cookbook was published three years ago, I don't think that that ingredient is a difficult one to find. Even our local Costco sells it! Anyway, making the cookie dough is straightforward. To mitigate against Milk Bar's sweet bias, I reduced the sugar by about a quarter: just over 100g each of the granulated sugar and brown sugar, keeping the glucose at 100g. This change didn't compromise taste nor texture, in my opinion.
My #20 scoop produced between 16 and 20 large blobs of dough which I divided across two sheet pans. The first batch I made turned out too brown and crisp: I baked it straight from the fridge at 340°F convection for 18 minutes. For the second batch, I reduced the oven temp a bit and reduced the baking time by a minute. I prefer these cookies slightly crisp on the outside and still soft in the middle, so I would aim for larger dough blobs. This provides the best texture so you can enjoy the contrast between the crunchy milk crumbs and the plump blueberries. Do look for larger dried blueberries: the Costco ones were not wild, and hence were larger, and stayed soft after baking.
The verdict? An excellent cookie that is true to its name, highlighting both blueberries and milk.