Set oven to 350° F
Spray pan with oil and toss with flour. Set aside.
In large bowl, cream butter. Gradually add in sugar, cream until light and fluffy.
Beat in eggs, one at a time.
Sift together cake flour, baking powder, and salt.
Alternate adding flour mixture and milk, blending each, but do not over mix.
Zest lemon, set aside zest for buttercream frosting.
Cut lemon in half and juice. Add juice to cake batter and set aside the rest for buttercream. Add zest to batter.
In a small bowl, mix 2 1⁄2 cups fresh blueberries with 1 tbsp cake flour. Toss blueberries until coated with flour. Gently fold in blueberries to cake batter.
Pour cake batter into 9x13 pan. Bake 20-25 minutes or until a toothpick inserted in the center comes out clean.
Set cake on a cooling rack until completely cooled.
Prepare buttercream.
In a medium saucepan lightly sprayed with oil, heat shredded coconut on medium low heat until very lightly toasted. Quickly remove from heat and set aside.
In a small bowl, blend together softened butter and powdered sugar.
Add lemon juice. If more liquid is needed to create the buttercream consistency, use milk.
Frost cooled cake with buttercream. Sprinkle cake with toasted coconut. Sprinkle cake with reserved 1 tbsp lemon zest. Top cake with reserved 1⁄2 cup fresh blueberries.
Slice and serve cake. Enjoy!