• Preheat the oven to 350° F. Line 12 muffin cups with paper liners.
• In the bowl of a stand mixer, combine the flour, sugar, baking powder and salt, and mix until evenly blended.
• To the dry ingredients, add the VERY soft butter, sour cream, egg, yolks and vanilla. Mix with a heavy duty scraper until ingredients are blended, then set mixer on stand and beat for about 20 seconds on medium, scraping bowl as needed. Alternatively, just mix everything together with a spoon and mix with a handheld mixer for about 20 seconds. I haven't tried mixing the batter fully by hand yet.
• Using a 2 ounce ice cream scoop, large cookie scoop or a heaping tablespoon, scoop the thick batter into the cups.
• Bake for 20-24 minutes or until cupcakes are brown around the edges and a skewer inserted comes out clean. Carefully remove from the muffin pan and let cool for 45 minutes while you make the ganache.

Whipped Chocolate Ganache

• Put the chopped chocolate in the stand mixer bowl.
• Heat the cream over the stove or in the microwave just until boiling, then pour it over the bowl. Cover the bowl and let stand for 5 minutes, then stir until chocolate has melted.
• Put the whole bowl in the refrigerator for about 30 to 40 minutes or until the mixture is cold. Keep an eye on it and don't let it get too cold or it will be too thick to whip.
• Set the mixer on the stand and beat with the whisk attachment until thick and creamy and peaks form.