Summarize:

Spray a 9in 9in (23cm 23cm) square pan, a 9 by 5 inches (23cm 13cm) loaf pan, or a 9in (23cm) round pan with baking spray and then cut a piece of parchment paper to fit the bottom of the pan. Try to use a metal cake pan since this conducts heat better than glass or ceramic. If you'd like to make plain cupcakes, put muffin liners into 16 to 18 cavities of a muffin tin. Put the cake on the center rack of your preheated oven and bake it for 45 minutes. The cake should become a rich golden color and start to pull away from the edges once it's baked. Since everyone's oven is a little different, it may take your oven more time to bake the cake, so don't worry if it needs up to 15 more minutes. You can also insert a toothpick or skewer into the center of the cake to see if it's done. The tester should come out clean and if it doesn't, bake the cake for a few more minutes before you check it again. If you're making plain cupcakes, check them after 20 minutes. Turn off the oven and wear oven mitts to take the cake out. Set the pan on a wire rack and leave the cake to cool completely before you take it out of the pan. You don't need to worry about the cake sticking to the pan since the parchment is on the bottom.
Preheat the oven to 350F (177C) and line a 9in (23cm) pan. Bake the plain cake for 45 to 60 minutes. Remove the cake and cool it on a wire rack for 1 hour.