Step 1

We prefer our  Small-Batch Vanilla Frosting  here because it makes exactly 2 cups, but you can use your favorite frosting recipe or store-bought.

Step 2

FOR THE CUPCAKES: Adjust oven rack to middle position and heat oven to 325 degrees. Line 12-cup muffin tin with paper liners. Microwave chocolate and oil together in bowl at 50 percent power, stirring often, until chocolate is melted, about 2 minutes; whisk smooth and let cool slightly. In separate bowl, whisk flour blend, baking powder, baking soda, xanthan gum, and salt together.

Step 3

In large bowl, whisk eggs and vanilla together. Whisk in sugar until well combined. Whisk in cooled chocolate mixture and sour cream until combined. Whisk in flour blend mixture until batter is thoroughly combined and smooth. Gently whisk in sprinkles until thoroughly incorporated.

Step 4

Portion batter evenly into prepared muffin tin. Bake until cupcakes are set on top and toothpick inserted into center of cupcakes comes out clean, 19 to 22 minutes, rotating muffin tin halfway through baking.

Step 5

Let cupcakes cool in muffin tin for 10 minutes, then transfer to wire rack and let cool completely, about 1 hour. (Unfrosted cupcakes can be stored in airtight container at room temperature for up to 1 day.)

Step 6

FOR THE FROSTING: Stir sprinkles into frosting. Spread or pipe frosting onto cupcakes before serving.