Preheat the oven to 350 degrees.
Beat butter and sugar in a large mixing bowl till creamy.
Add flour, cocoa powder, salt, and eggs. Beat till smooth. Add buttermilk, lemon
juice, and vanilla and blend well. (Mixture may appear curdled.)
Pour filling into a 9" pie crust. I like to use a deep dish.
Bake for 30 minutes
Allow cooling completely on the counter
Place into the fridge overnight
Using a small pot, bring the heavy cream to a boil
Pour over the chocolate chips in a medium bowl and let sit for 1 minute
Whisk until smooth
Spread evenly onto the top of the buttermilk pie
Pipe dollops of the whipped cream onto the edge of the pie
Sprinkle with mini chocolate chips
Chill for an hour before enjoying it!