Line 2 standard size muffin pans with paper liners.
Combine 1 cup flour, sugar, undissolved yeast and salt in a large bowl.
Heat water, milk and butter until very warm (120º to 130ºF).
Gradually add the milk mixture to flour mixture. Beat 2 minutes at medium speed in an electric mixer, scraping bowl occasionally.
Add egg and 1 cup flour; beat 2 minutes at high speed.
Stir in enough remaining flour to make stiff batter.
Gently fold in the chilled blueberries with a rubber spatula.
Use a medium cookie scoop sprayed with nonstick cooking spray to distribute the dough between into the prepared muffin pans. (Muffin cups should be half full).
Cover; let rise in warm, draft-free place until doubled in size, about 30 minutes.
While the muffins are rising, make the walnut topping by combining the brown sugar, flour, walnuts, butter and cinnamon with a pastry blender or two forks until you create pea-sized crumbs. Refrigerate the topping until read to use.
Once the muffins have risen, sprinkle with the walnut topping.
Bake at 375ºF for 22-25 minutes until golden brown. Remove from pan; cool on wire rack.
Once the muffins are cool, stir together the powdered sugar, lemon juice and 1 teaspoon of milk at a time until you reach the desired consistency. You want the glaze to be just thin enough to drizzle over the muffins.