Prep Like a Pro: Preheat your oven to 350°F (177°C) and grease a 9x13-inch baking pan. Pro tip: Use a glass pan if you want easy cleanup or a metal one with a lid for transporting leftovers.
Mix the Dry Ingredients: In a large bowl, whisk together the flour, baking powder, baking soda, salt, cinnamon, and nutmeg. Set this aside while you tackle the wet ingredients.
Combine the Wet Ingredients: In another bowl, whisk the oil, sugars, applesauce, eggs, and vanilla until smooth. Pour this mixture into the dry ingredients and stir until just combined. Don’t overmix—your batter should have a few lumps.
Fold in the Zucchini: Grab your shredded zucchini (no peeling or blotting required!) and gently fold it into the batter. The zucchini might make the batter look a little green—that’s totally normal.
Bake to Perfection: Pour the batter into your prepared pan and spread it evenly. Pop it in the oven for 45–50 minutes. Around the 30-minute mark, loosely cover the cake with foil to prevent over-browning. When a toothpick comes out clean, you’re good to go!
Brown the Butter (The Secret Sauce!): While the cake cools, melt your butter in a light-colored skillet over medium heat. Stir constantly until it turns golden-brown and smells nutty. Pour it into a bowl and chill until solidified.
Whip Up the Frosting: Beat the solidified brown butter and cream cheese until smooth. Add the powdered sugar, vanilla, and salt, and mix until fluffy. Spread this dreamy frosting over the cooled cake.