Preheat the oven to three hundred and fifty degrees, and grease a cake pan.
In a large bowl, blend three cups of Bisquick and one-half cup of white sugar together.
Add one-half cup of cubed, cold butter, and mix using a pastry blender until the flour becomes crumbly. Fold in one cup of blueberries.
In a separate bowl, using an electric mixer, beat one cup of heavy cream, two large eggs and two tablespoons of lemon zest.
Mix the wet and dry ingredients together until combined. If the mixture seems to dry, add more cream, and if too wet, add more Bisquick.
Place the dough-like mixture into the prepared cake pan and smooth out evenly.
Brush the top with the beaten egg and bake for approximately twenty minutes, or until golden brown. Prepare the glaze.
In a medium-size bowl, combine two tablespoons of melted butter, one cup of powdered sugar, one tablespoon of lemon zest, and three tablespoons of lemon juice. Mix until smooth.
Drizzle the glaze over the top of the cooled scone cake and cut into triangles. Enjoy!