Step 1

Preheat the oven to 350 F and spray or grease a 9-inch square baking pan.

Step 2

In a large bowl, whisk together flour, sugar and baking powder. Cut butter into small pieces. Add egg, milk, butter and lemon peel; mix just until dry ingredients are moistened. You may need to finish mixing with your hands to get all the flour incorporated. the batter will be very thick.

Step 3

Fold in the blueberries. Because the batter is so thick, this may take a few minutes. Spread into a greased 9-in. square baking pan.

Step 4

For topping, combine sugar, flour, walnuts and cinnamon in a mini food processor or bowl. Add butter and process, or cut in if doing by hand, until mixture is crumbly. I like to do this with my fingers so I can tell when it's ready by touch. Sprinkle over batter. Bake at 350 degrees F for 40-45 minutes or until cake tests done.

Step 5

For drizzle, combine the powdered sugar and milk. If too thick, add a few drops of additional milk at a time until it reaches drizzling consistency. Drizzles over the top of the cake and allow to sit until sugar solidifies.