Whisk together the eggs, sugar, pumpkin puree, butter and instant coffee together in a large bowl. Then mix together the flour, baking soda, salt, cinnamon, ground ginger, nutmeg, allspice and cloves together in a separate bowl, and add to the pumpkin mixture and mix together.
Pour into a buttered, 9×5 inch loaf pan, and bake for 75-80 minutes at 350 degrees until fully cooked. Allow it to cool for 15 minutes in the pan, then remove from the pan and cool completely on a cooling rack.
Make the buttercream by whipping together the butter, confectioner’s sugar, vanilla extract, instant coffee and pumpkin in a bowl with an electric mixer until light and fluffy.
Cut the loaf into slices, and then squirt a small amount of buttercream into the bottom of the mug, and then layer the slices into a Starbucks mug with buttercream in between each layer, until you reach the top of the mug. Then in a piping bag fitted with a star-shaped piping tip, pipe on some more buttercream to look like whip cream and sprinkle on some cinnamon.