Pre-Cooking Prep
Preheat oven to 350°F (175°C).
Grease an 8×8-inch baking pan or line with parchment paper.
Peel, core, and finely chop apples.
Make the Batter
In a large bowl, whisk brown sugar, oil, plant-based milk, vinegar, and vanilla until smooth.
Stir in chopped apples.
In a separate bowl, whisk flour, baking soda, cinnamon, nutmeg, and salt.
Add dry ingredients to wet ingredients and mix just until combined.
Fold in nuts if using.
Bake
Pour batter evenly into prepared pan and smooth the top.
Bake for 40–45 minutes, until a toothpick inserted in the center comes out clean or with moist crumbs.
Cool in the pan for 15 minutes before slicing.
Doneness & Texture Check
Top lightly golden and set
Center firm, not wet or gummy
Toothpick shows crumbs, not raw batter