Start by bringing all the ingredients to room temperature if they were refrigerated. It's best to keep the refrigerated ingredients on the counter 30 minutes prior to baking.
Preheat the oven to 350 °F (180 °C). Grease an 8 inch round pan with butter or line it with parchment paper. I used baking spray which worked great.
Whisk together flour, sugar, cocoa, baking soda & salt in a large mixing bowl. Do not use a stand or a hand mixer. This step is important as whisking the mixture will aerate it well and you will get a perfect cake with great crumb.
In a separate small bowl combine water, oil, vinegar, instant coffee & vanilla extract.
Add wet ingredients to the dry ingredients & whisk till just combined. A smooth batter is not necessary, few lumps are fine.
Pour the batter into the prepared 8 inch round pan.
Tap the pan gently 2-3 times to remove air bubbles and batter spreads evenly.
Bake in preheated oven at 350 °F (180 °C) for 20-25 mins or till a toothpick inserted into the cake comes out clean
Cool the cake in the pan on the rack for 15 minutes, then invert it on the rack.
Leave it upside down to cool, it helps in flattening any dome shape.
I usually bake three layers by baking this recipe thrice separately or in 3 pans ahead of time.
Then I freeze these layers wrapped in cling film till 24 hours prior to the assembling and decorating.
You can decorate the cake as per your wish using basic decorating guidelines at assembling and frosting the cake.