For the Cake:
For the Topping:
Preheat oven to 375° F.
First, make the topping. Combine all Topping dry ingredients and then cut in the butter until the mixture resembles coarse crumbs. You can double this part too, like we did.
Next, make the cake. Sprinkle berries with 1 ½ tablespoons of the flour mix. Toss gently. Set aside.
Cream butter and sugar. Add the egg and vanilla extract. Beat mixture until fluffy and light. Stir in the remaining dry cake ingredients alternately with the milk. Then, stir in the lemon rind. Spoon stiff batter over floured blueberries and fold gently until just mixed.
Turn into a buttered 8- or 9-inch square pan that has been dusted with some dry bread crumbs. Then, sprinkle cake batter with nuts and the prepared topping.
Bake on the center rack in the preheated for 40-45 minutes or until a knife inserted comes out with just a few crumbs on it. Allow to cool in the pan for at least 30 minutes before serving.