Cake – How to calculate an increase in pan sizes for a cake recipe

I have halved cake recipes before without issue. The most complicated thing to worry about is halving an odd number of eggs, but this question addresses that. The finished product was indistinguishable from the full recipe.

Edit

One thing to note. In your specific case, because it's a two-layer cake, halving is simple because you're only cooking a single layer. Halving other cakes, such as a pound cake, or a bundt cake involves adjustments to the cooking time. A halved cake will cook much quicker, and could possibly need a lower temperature as well as a decreased cooking time.

it's probably there to add depth to the flavor, since chocolate and coffee complement each other so well. i've used the instant kind in similar recipes and it's just fine.