Preheat oven to 350°. Let eggs and buttermilk stand at room temperature 30 minutes.
Cream butter and granulated sugar until light and fluffy, about 5 minutes. Add eggs, one at a time, beating well after each addition. Stir in lemon peel. In another bowl, sift together 3 cups flour, baking powder, baking soda and salt. In a separate bowl, combine 3/4 cup lemon juice, buttermilk and vanilla. Add flour and buttermilk mixture to batter alternately, beating well after each addition, beginning and ending with flour mixture. Stir in crushed cookies.
Toss blueberries and remaining flour; fold into batter, taking care not to crush berries. Pour into two greased and floured 8x4-in. loaf pans lined with parchment paper. Bake until a toothpick inserted in center comes out clean, 50-60 minutes. Cool 10 minutes.
Stir glaze ingredients together. Remove cakes from pans and place on wire racks. Drizzle glaze over cakes, allowing some to run down sides. Sprinkle with lemon peel and, if desired, additional crushed cookies.