For the dough: in a stand mixer fitted with the paddle attachment, mix together 5 pounds crème cake base, 2 pounds bread flour, 1 pound 8oz softened butter, and 12oz whole eggs. Mix 1-2 minutes on low speed, scrape bowl and add 6oz water, mix on low speed for two minutes. Pat dough into a circle, cover with plastic wrap, and chill completely.
For the toaster pastries: Roll chilled dough to ¼ inch thick. Cut into 3x5 squares and chill dough again. Pipe filling on prepared dough squares, mist with water and top with another square of dough. Crimp edges and pierce top to allow for steam. Bake at 350F until golden brown. Let cool completely. Spread with warmed white flat icing and top with sprinkles before icing sets.