Combine the milk and vinegar in a glass and stir. Place in the fridge for 20 minutes, and you'll have homemade buttermilk!

Place the flour, baking powder, baking soda, salt, ginger, cinnamon, nutmeg and cloves in a bowl and whisk together. Set aside.

Place the butter and brown sugar in a bowl and beat with an electric mixer until pale and fluffy. Add the eggs one at a time, beating with each addition.

Add the flour mixture in 3 additions, alternating with the buttermilk. Then add and combine the pumpkin puree. Add a few drops of orange food colouring to brighten the batter. Set aside.

Slice the Starbucks Pumpkin Spice Latte Cake into 6 thick slices. Cut 2 triangle-shaped eyes out of one slice, then use these pieces of cake as stencils for 2 more slices. You should have 3 pairs of eyes in total. Repeat with the remaining 3 slices for the mouth. Save 1 large scrap of cake for the pumpkin's stem.

Grease and flour 3 9-inch round baking pans. In one pan, arrange the pairs of eyes back to back. Repeat with the mouth in the second pan. Pour the pumpkin cake batter on top, fully covering the cake pieces. Pour the remaining cake batter into the third pan.

Bake the cakes at 350F for 45-60 minutes, until the cakes are fully cooked. Let cool in the pans for 30 minutes, then transfer to a wire rack and allow to fully cool.

To assemble, place the smallest cake face down on a tray lined with parchment paper. Place the cake with the mouth on top (right side up), checking the bottom of the cake to check the alignment of the mouth. Flatten the surface of the cake, then place the cake with the eyes on top, checking the bottom of the cake to ensure that the eyes and mouth are facing the same direction. Place a marker on the tray to remind yourself which way the face is facing.

Carve the cake into a sphere.

Mix a small amount of buttercream with some cocoa powder to dye it brown. Coat the cake in a thin layer of the pumpkin spice buttercream, then coat in another thicker layer.

Make grooves in the buttercream to mimic a pumpkin. Cover the stem in the chocolate buttercream and stick it on top of the cake.

Slice the cake in half to reveal the jack-o-lantern face, and enjoy!