Preheat oven to 360 F / 180 C. Line 2 cookie sheets with parchment.
In a small bowl, cover blueberries with about a cup of hot water and let it sit for 10 minutes, drain and set aside.
In a small saucepan, melt butter over low heat. The butter should just be melted warm to preserve the moisture. Alternatively you can also melt the butter in a microwave oven for 2-3 minutes until butter is melted, stirring every minute until butter turns into a liquid.
In a medium bowl, stir together the flour, baking powder, baking soda, and salt.
Place sugars in a mixer bowl, pour in melted butter. Mix with a paddle attachment on medium until the ingredients are well incorporated. Add in vanilla extract, and eggs one at a time, mix well after each addition.
With the mixer on low speed, incorporate flour mixture until it is no longer dry, about 20 seconds, scrape bowl. Add in the rest of the ingredients - nuts, chocolate, and blueberries to incorporate, just until they have been well distributed into the dough, avoid over-mixing.
Scoop cookies into about 2 tablespoons each or use a #24 cookie scoop. Place cookies about 3" apart on the parchment lined cookie sheet, sprinkle salt on top of each one.
Bake cookies one tray at a time in preheat oven for 10-14 minutes, rotating the pan halfway through. Cookies should be slightly golden around the edges, gooey and soft in the middle. Don't over-bake for soft and chewy cookies! Cool cookies before removing them from the tray.