Grease a 3-cup bundt pan well with baking spray and set aside. In a small bowl, whisk together the flour, cocoa powder, baking soda, and salt and set aside.
In a medium-sized bowl cream together the butter and brown sugar with a hand mixer. The mixture will not be completely smooth, but instead, have a slightly crumbly texture.
Add in the eggs one at a time until fully combined. Then add in the vanilla and mix until combined, scrape down the sides of the bowl.
In a small bowl, whisk together the melted chocolate1 and the sour cream.
Add half of the flour mixture to the egg mixture until incorporated then add half of the sour cream/chocolate mixture and mix until combined. Scrape down the sides of the bowl then repeat with the remaining flour mixture and sour cream mixture.
Add the batter evenly into the bundt pan and smooth out the top.
Preheat the air fryer to 320°F. Place the bundt pan in the air fryer basket and cook for 14 minutes. Rotate 180° and air fry for an additional 10 to 14 minutes2 or until a toothpick inserted into the center comes out clean.
Let the bundt cool in the pan for 10 minutes, invert the pan to release the cake, and let cool completely on a wire rack.
Once the bundt is cool, make the ganache glaze by adding the finely chopped chocolate to a heatproof bowl.
Add the cream to a small saucepot over medium-low heat and bring it to scalding or just when the first bubbles pop up to the surface. The temperature of the cream will be 160°-170°F. Pour the cream over the chopped chocolate and let it sit for 5 minutes.
Whisk the ganache until it is smooth. Let it cool on the counter until it is thickened but still pourable, about 5 to 10 minutes.
Pour the ganache over the bundt cake. Decorate with sprinkles if desired. Serve as is or with fresh whipped cream and berries on the side.