Step 1

Preheat to 350°F. Line a 12-cup muffin tin with muffin cups.

Step 2

In a medium bowl, whisk together the flours, baking powder, baking soda, sea salt, cinnamon and nutmeg.

Step 3

In a large bowl, using an electric mixer, beat the butter until smooth, about 2 minutes on medium speed. Add the brown sugar and beat until light and fluffy, about 3 minutes. Add the eggs, one at a time, beating to combine after each addition. Beat in the sour cream and vanilla extract. Reduce speed to low and add in the dry ingredients, in two separate additions. Beat until just combined and incorporated.

Step 4

Divide the batter into the prepared muffin cups, filling each 2/3 full.

Step 5

Bake the cupcakes for 20-23 minutes or until a toothpick inserted into the center comes out clean. Let cool completely before frosting.

Step 6

For the frosting, beat the butter and brown sugar on medium-high speed until light and fluffy. Add in the rest of the ingredients and mix on low speed to combine. Increase speed and beat frosting until fluffy, about 2-3 minutes.

Step 7

Frost cupcakes and decorate as desired.