Preheat the oven to 350°F (175°C). Grease two 8- or 9-inch round cake pans and line the bottoms with wax paper.

In a large mixing bowl, whisk together the all-purpose flour, Ghirardelli sweet ground chocolate and cocoa, granulated sugar, baking soda, cream of tartar, and optional salt.

Add 1 cup of buttermilk and softened butter to the dry mixture. Beat on medium speed for about 2 minutes until creamy.

Incorporate remaining buttermilk, eggs, and vanilla extract. Mix on medium speed until smooth and fully blended.

Divide the batter evenly between the prepared cake pans and bake for 30-45 minutes until a toothpick comes out clean.

Allow cakes to cool in their pans for 10-15 minutes, then transfer to a wire rack to cool completely.

For frosting, cream together shortening, softened butter, and vanilla extract until fluffy. Gradually add confectioners' sugar, mixing well, then add milk to reach a spreadable consistency.

Cut out mini layers from each cake using a sharp metal cookie cutter. Stack layers with buttercream frosting in between.

Decorate the frosted mini cakes with sprinkles, mini chocolate eggs, or pastel decorations to enhance their festive appearance.