Preheat oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.

In a bowl, whisk together flour, baking powder, baking soda, salt, and chai spice mix.

In a large mixing bowl, cream together butter, brown sugar, and granulated sugar until light and fluffy.

Add eggs one at a time, mixing well after each addition. Stir in vanilla.

Alternate adding the flour mixture and buttermilk to the butter mixture, starting and ending with flour, mixing until just combined.

Divide batter evenly between prepared pans and smooth the tops.

Bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean.

Allow to cool in pans for 10 minutes, then turn out onto wire racks to cool completely.

For the frosting, beat together cream cheese and butter until smooth. Gradually add powdered sugar and vanilla, mixing until well combined. Adjust consistency with milk if necessary.

Once cakes are cool, spread frosting between cake layers and over the top and sides. Decorate as desired.