Preheat oven to 350°F (175°C).

Cut parchment paper for the bottom of your two 9-inch cake pans and spray with gluten-free cooking spray.

Add the white vinegar (or lemon juice) to the 1 cup of milk or dairy-free milk to make the homemade buttermilk.

In a medium-sized bowl, add gluten-free flour, salt, baking soda, gluten-free baking powder, cocoa powder, and cinnamon. Stir to combine the ingredients.

In a large bowl, cream the softened butter and granulated sugar with a mixer until fluffy.

Add the eggs and pure vanilla extract to the butter mixture and mix until fully combined.

Add the flour mixture to the butter mixture and mix until fully combined. Scrape down the sides if needed.

Add the homemade buttermilk to the cake batter and mix until fully combined.

Add the boiling water to the batter and mix until fully combined.

Pour half of the batter into the first greased 9-inch cake pan and then pour the rest of the batter into the second greased 9-inch cake pan.

Bake on the middle rack for 30-35 minutes. Check the center of the cake by inserting a toothpick to make sure it is done.

Allow the cakes to cool fully before frosting.

In a large bowl, cream butter until smooth with a mixer.

Add the pure vanilla and almond extract to the butter. Mix until fully combined.

Add the cocoa powder and mix until fully combined.

Add the powdered sugar one cup at a time to the butter mixture and mix until fully combined.

Add the milk to the frosting and beat it until smooth and spreadable.

Place the first cake with the shiny side down on a plate or a cake plate.

Frost the top of the first cake.

Place the second cake on top of the frosted first cake, the shiny side down.

Frost the top and side of the cake with the remaining frosting.