Preheat the oven to 350°F (175°C). Grease a 9-inch (23 cm) round cake pan and line the bottom with parchment paper, or lightly oil and dust with flour.

Dry ingredients

In a large bowl, whisk together the all-purpose flour, granulated sugar, baking powder, baking soda, and fine salt until evenly combined.

Wet ingredients

In a separate bowl, whisk the room-temperature vegan yogurt, olive oil, fresh orange juice, orange zest, vanilla extract, and aquafaba (or flax egg) until smooth and homogenous.

Combine

Make a well in the center of the dry ingredients and pour in the wet mixture. Using a rubber spatula or wooden spoon, gently fold until just combined and no large streaks of flour remain. Do not overmix — the batter should be smooth and pourable.

Bake

Pour the batter into the prepared pan and smooth the top. Bake for 35–45 minutes, or until the top is golden, a toothpick inserted into the center comes out with a few moist crumbs (not wet batter), and the cake springs back lightly when touched.

Cool

Let the cake cool in the pan for 10–15 minutes. Run a knife around the edge, invert onto a wire rack, remove the parchment, and let cool completely before glazing or serving (about 1 hour).

Citrus-Honey (Vegan) Yogurt Topping

While the cake cools, prepare the topping by stirring the unsweetened vegan yogurt with agave syrup, orange zest, lemon juice, and a pinch of fine sea salt until smooth and slightly thickened. Taste and adjust sweetness with more agave if desired. Chill until ready to serve.

Glaze (optional)

If using glaze, whisk the powdered sugar with the 1/4 cup orange juice until smooth and loose but pourable. If too thick, add a little more juice; if too thin, add more powdered sugar. When the cake is cool, spoon the glaze over the top, letting it drip down the sides. Sprinkle with orange zest.

Finish & Serve

If using nuts, toast sliced almonds or pistachios in a dry skillet over medium heat for 3–4 minutes, shaking often, until fragrant and lightly browned. Let cool.

Place the cooled cake on a serving plate. Spoon the citrus-honey vegan yogurt across the top or serve alongside individual slices. Garnish with toasted nuts and thin orange slices or segments. Serve at room temperature.