Preheat the oven to 350°F.
In a bowl, combine room t° milk, oil, vanilla extract & both sugars. Whisk until the sugar has dissolved.
In a separate bowl, combine all the dry ingredients. Mix the dry ingredients into the wet ingredients using an electric whisk or hand whisk. Add grated carrots & walnuts (if using) & fold the batter gently.
Divide the batter between the prepared cake pans & bake for roughly 40–45 min. or longer until firm to the touch. Insert a toothpick to check if the crumb is dry.
Cool the sponge cakes completely on a cooling rack before using.
