Prep the pan and oven: Heat the oven to 350°F (175°C). Line an 8-inch square pan or 9-inch round pan with parchment and lightly oil the sides.

Mix dry ingredients: In a medium bowl, whisk flour, baking powder, baking soda, salt, and cinnamon until well combined.

Whisk wet ingredients: In a large bowl, whisk eggs and sugar until slightly frothy, about 30 seconds. Add yogurt, applesauce, oil, vanilla, and citrus zest if using. Whisk until smooth.

Combine: Add the dry ingredients to the wet and stir with a spatula just until no dry streaks remain. Do not overmix.

Fold in moisture boosters: Gently fold in grated zucchini, mashed banana, or berries. If using zucchini, pat it dry first to avoid excess water.

Batter to pan: Pour the batter into the prepared pan and smooth the top. Sprinkle nuts or turbinado sugar if you like a little crunch.

Bake: Bake for 22–28 minutes, depending on your pan and add-ins. The cake is done when the center springs back lightly and a toothpick comes out with a few moist crumbs.

Cool: Let the cake cool in the pan for 10 minutes, then lift it out onto a rack to finish cooling. This helps maintain moisture without getting soggy.

Serve: Enjoy plain, dust with powdered sugar, or add a thin smear of Greek yogurt mixed with a touch of honey and lemon.