In small microwave safe bowl melt 4 ounces of unsweetened baking chocolate until stirrable (about 45 seconds on high). Set aside to cool.In a large bowl with an electric mixer beat 1 cup (2 sticks) of regular (salted) butter and 1 ½ cups of white sugar until fluffy (about 1 to 2 minutes). When melted chocolate is cooled, drizzle it over the butter/sugar mixture. Add 1 teaspoon of vanilla extract. Beat the mixture thoroughly until combined (on a Kitchen Aid mixer, you will be using the whisk attachment).Turn your mixer to a medium speed and over a period of 15 to 20 minutes add in the four eggs, one at a time, leaving about 5 minutes between each egg addition. Once the pie filling is well mixed, pour it into the baked pie shell, scraping every last speck of it out of the bowl. Smooth out the pie filling and place pie in the refrigerator to chill for at least two hours (preferably longer).Plop a heap of whipped cream and garnish with a few chocolate curls if you’re feeling sassy.