Preheat and Prep: Fire up the oven to 350°F. Spray that 9x13 pan with flour spray—trust me, no sticking drama.
Make the Batter: Chuck carrots, sugar, eggs, and oil in the blender. Zap it until smooth, like 90 seconds. Whisk flour, baking powder, salt, and cinnamon in a big bowl. Dump in the carrot mixture, stir gently. Add nuts or raisins if you want. Tap the pan to even it out.
Bake: Pop it in and bake until golden, toothpick clean—30-35 minutes. Allow to cool on a rack for one hour. Your house? Pure spice heaven.
Make the Frosting: Saucepan time: mix condensed milk, cream, cocoa, chips, butter, salt. Stir like crazy over medium heat until it's pudding-thick, 10-12 minutes. Spatula test: bottom shows for a sec. Cool a bit, stir occasionally.
Frost and Chill: Slap that warm frosting on the cooled cake. Sprinkles? Why not. Let it sit for an hour before cutting. Leftovers at room temp for 3 days, easy.