Prep the pan and oven. Heat oven to 350°F (175°C). Grease an 8-inch square baking pan and line with parchment, leaving a slight overhang for easy lifting.

Mix the dry ingredients. In a large bowl, whisk flour, baking powder, baking soda, salt, cinnamon, and nutmeg until well combined. This helps prevent clumps and ensures even rise.

Whisk the wet ingredients. In a separate bowl (or a large measuring cup), whisk applesauce, oil, eggs, vanilla, and both sugars until smooth and slightly glossy.

Combine. Pour the wet mixture into the dry ingredients. Stir with a spatula until just combined. If the batter seems very thick, add milk 1 tablespoon at a time. You’re aiming for a thick, scoopable batter that falls off the spoon in slow ribbons.

Fold in extras. If using nuts, raisins, or chocolate chips, fold them in gently. Do not overmix.

Fill the pan. Spread the batter evenly in the prepared pan. Smooth the top with a spatula so it bakes evenly.

Bake. Bake for 28–35 minutes, or until the top is set, the edges are lightly browned, and a toothpick inserted in the center comes out with a few moist crumbs.

Cool. Let the cake cool in the pan for 10 minutes, then lift it out to a wire rack to cool completely. This helps keep the crumb tender.

Finish and serve. Dust with powdered sugar or drizzle with glaze. Slice into squares. Enjoy warm or at room temperature.