It's Raining Cupcakes by Lisa Schroeder

Isabel's mom is opening a cupcake shop called "It's Raining Cupcakes" in a town called Willow. But another store called "Beatrice Brownies" pops up! Also Isabel is facing the worries of a baking competition and her mother giving up the cucpake shop! Things are even worse later when a reporter comes to their house and Sophie, Isabel's best friend, seems to ruin her answer to a question! Will Isabel make her mother think otherwise about the shop, make up with Sophie, and win the contest? - Katherine