Prepare the cupcakes: Preheat oven to 350 degrees with rack in center. Place chocolate in a medium heatproof bowl, and set it over a medium saucepan of barely simmering water; stir chocolate until melted and smooth. Remove bowl from heat, and set aside to cool slightly. (I melted my chocolate in the microwave for about 45 seconds instead.)
Meanwhile, whisk together flour, baking powder, baking soda, and salt in a medium bowl; set aside.
In the bowl of an electric mixer fitted with the paddle attachment, cream butter and sugar on medium speed, scraping sides of bowl as needed, until light and fluffy. On low speed, mix in melted chocolate. Increase speed to medium, and add eggs, one at a time, mixing well after each addition. Add vanilla, and beat until mixture is creamy and color has lightened slightly, about 1 minute. Mix in sour cream. On low speed, add half of reserved flour mixture, beating until just incorporated. Mix in 1/2 cup water. Add remaining flour mixture, and mix until just incorporated.
Line a cupcake pan with paper liners. Fill each liner with enough batter to come 1/8 inch from top, about 1/3 cup. (I filled mine slightly less than that, about 2/3 full.) Bake, rotating pans halfway through, until tops are firm and a cake tester inserted in the center comes out clean, about 20 minutes. Transfer cupcakes to a wire rack to cool in pan for 10 minutes.
Use a small knife to loosen any tops stuck to the pan. Carefully invert cupcakes onto the wire rack. Turn cupcakes right side up, and let cool completely.
Prepare the frosting: In a large heatproof bowl, combine 1/4 cup water and egg whites and beat until foamy. Add sugar and cream of tartar. Using a handheld electric mixer, beat on high speed until foamy again, about 1 minute. Set bowl over a pan of barely simmering water. Beat on high speed until frosting forms stiff peaks, about 12 minutes; frosting should register 160 degrees on a candy thermometer. (Mine never reached 160 degrees. Just beat until the sugar is no longer gritty and the mixture feels warm to the touch.) Remove from heat; stir in vanilla and almond extracts, and beat for 2 minutes more or until frosting thickens. (A tip from another site recommended putting frosting into a stand mixer at this point and whisking until the proper consistency is reached. I found this to be helpful and a great rest for my arm. It took about 7 minutes to reach the stiff peaks consistency I was going for.)
Transfer frosting to a large pastry bag fitted with a 1/2-inch plain pastry tip. Leaving a 1/8-inch border on each cupcake, pipe a spiral of frosting into a 2-inch-high cone shape, using about 1/2 cup of frosting per cupcake. Transfer cupcakes to a baking sheet, and freeze for approximately 2 hours before preparing the chocolate coating.
Prepare the chocolate coating: Combine chocolate and oil in a medium heat-proof bowl set over a medium saucepan of barely simmering water (or microwave in increments of 30 seconds); stir/whisk until melted and smooth. Transfer to a deep container (as tall as your cupcakes/frosting at least), and let cool about 15 minutes.
Holding each cupcake by its bottom, dip cupcake in the chocolate to coat frosting, allowing excess to drip off. Transfer to a baking sheet fitted with a wire rack. Spoon more coating around edge of cupcake and any exposed frosting; none of the frosting should show.
Refrigerate for 30 minutes to let coating set. Cover, and refrigerate for 2 hours more. Serve cold. Cupcakes can be refrigerated for up to 3 days
