Preheat oven to 350 degrees F. Grease well a 9×13'' inch pan.
Chop the butter and the unsweetened baking chocolate into chunks and place together in a microwave safe bowl.
Microwave in 30 second intervals, stirring in between, until melted. Set aside to cool, stirring occasionally.
In a large bowl beat the eggs, sugar, and vanilla until light and fluffy. While mixing, slowly add the melted chocolate.
In a separate small bowl combine the flour and baking powder. Stir the flour into the chocolate batter, just until combined.
Pour batter into greased pan and bake for 20-30 minutes or until a knife poked in the center comes out clean.
Remove from oven and allow to cool completely.
Once brownies are cool I like to cut off and remove the very outer edge where a "crust" sometimes forms. Then use a fork to fluff the mixture into crumbs.
Take a small cookie scoop (or just use your hands) to roll the brownie crumbs into 30-35 small balls.
Place them on a large, parchment lined baking sheet. Place in the freezer for 20-30 minutes or until firm.
Melt the chocolate chips and butter in a double boiler or in the microwave until smooth. Use a spoon to roll the brownie balls in the melted chocolate--I remove them with a fork to allow the excess chocolate to drip off.
Place the truffles carefully on parchment paper. At this point you could add sprinkles, if desired.
Refrigerate until set. These are best stored in the fridge. Remove 5 minutes before serving.